Code Analysis Warnings for Managed Code by CheckId
The following table lists Code Analysis warnings for managed code by the CheckId identifier of the warning.
When a static member of a generic type is called, the type argument must be specified for the type. When a generic instance member that does not support inference is called, the type argument must be specified for the member. In these two cases, the syntax for specifying the type argument is different and easily confused.
A class declares and implements an instance field that is a System.IDisposable type, and the class does not implement IDisposable. A class that declares an IDisposable field indirectly owns an unmanaged resource and should implement the IDisposable interface.
System.Collections.Generic.List<(Of <(T>)>) is a generic collection that is designed for performance, not inheritance. Therefore, List does not contain any virtual members. The generic collections that are designed for inheritance should be exposed instead.
A type contains a delegate that returns void, whose signature contains two parameters (the first an object and the second a type that is assignable to EventArgs), and the containing assembly targets Microsoft .NET Framework 2.0.
Inference is how the type argument of a generic method is determined by the type of argument that is passed to the method, instead of by the explicit specification of the type argument. To enable inference, the parameter signature of a generic method must include a parameter that is of the same type as the type parameter for the method. In this case, the type argument does not have to be specified. When using inference for all type parameters, the syntax for calling generic and non-generic instance methods is identical; this simplifies the usability of generic methods.
The more type parameters a generic type contains, the more difficult it is to know and remember what each type parameter represents. It is usually obvious with one type parameter, as in List<T>, and in certain cases that have two type parameters, as in Dictionary<TKey, TValue>. However, if more than two type parameters exist, the difficulty becomes too great for most users.
A nested type argument is a type argument that is also a generic type. To call a member whose signature contains a nested type argument, the user must instantiate one generic type and pass this type to the constructor of a second generic type. The required procedure and syntax are complex and should be avoided.
An externally visible method contains a reference parameter of type System.Object. Use of a generic method enables all types, subject to constraints, to be passed to the method without first casting the type to the reference parameter type.
The default value of an uninitialized enumeration, just as other value types, is zero. A nonflags-attributed enumeration should define a member by using the value of zero so that the default value is a valid value of the enumeration. If an enumeration that has the FlagsAttribute attribute applied defines a zero-valued member, its name should be "None" to indicate that no values have been set in the enumeration.
Event handler methods take two parameters. The first is of type System.Object and is named "sender". This is the object that raised the event. The second parameter is of type System.EventArgs and is named "e". This is the data that is associated with the event. Event handler methods should not return a value; in the C# programming language, this is indicated by the return type void.
To broaden the usability of a collection, implement one of the generic collection interfaces. Then the collection can be used to populate generic collection types.
When a base type is specified as a parameter in a method declaration, any type that is derived from the base type can be passed as the corresponding argument to the method. If the additional functionality that is provided by the derived parameter type is not required, use of the base type enables wider use of the method.
Constructors on abstract types can be called only by derived types. Because public constructors create instances of a type, and you cannot create instances of an abstract type, an abstract type that has a public constructor is incorrectly designed.
A public or protected type implements the addition or subtraction operators without implementing the equality operator.
The Common Language Specification (CLS) defines naming restrictions, data types, and rules to which assemblies must conform if they will be used across programming languages. Good design dictates that all assemblies explicitly indicate CLS compliance by using CLSCompliantAttribute . If this attribute is not present on an assembly, the assembly is not compliant.
The .NET Framework uses the version number to uniquely identify an assembly, and to bind to types in strongly named assemblies. The version number is used together with version and publisher policy. By default, applications run only with the assembly version with which they were built.
ComVisibleAttribute determines how COM clients access managed code. Good design dictates that assemblies explicitly indicate COM visibility. COM visibility can be set for the whole assembly and then overridden for individual types and type members. If this attribute is not present, the contents of the assembly are visible to COM clients.
When you define a custom attribute, mark it by using AttributeUsageAttribute to indicate where in the source code the custom attribute can be applied. The meaning and intended usage of an attribute will determine its valid locations in code.
Attributes can define mandatory arguments that must be specified when you apply the attribute to a target. These are also known as positional arguments because they are supplied to attribute constructors as positional parameters. For every mandatory argument, the attribute should also provide a corresponding read-only property so that the value of the argument can be retrieved at execution time. Attributes can also define optional arguments, which are also known as named arguments. These arguments are supplied to attribute constructors by name and should have a corresponding read/write property.
Make sure that each of your namespaces has a logical organization, and that a valid reason exists for putting types in a sparsely populated namespace.
Passing types by reference (using out or ref) requires experience with pointers, understanding how value types and reference types differ, and handling methods with multiple return values. Also, the difference between out and ref parameters is not widely understood.
Indexers (that is, indexed properties) should use a single index. Multidimensional indexers can significantly reduce the usability of the library.
A public or protected method has a name that starts with "Get", takes no parameters, and returns a value that is not an array. The method might be a good candidate to become a property.
Use a parameter array instead of repeated arguments when the exact number of arguments is unknown and when the variable arguments are the same type or can be passed as the same type.
Methods that use default parameters are allowed under the CLS; however, the CLS lets compilers ignore the values that are assigned to these parameters. To maintain the behavior that you want across programming languages, methods that use default parameters should be replaced by method overloads that provide the default parameters.
An enumeration is a value type that defines a set of related named constants. Apply FlagsAttribute to an enumeration when its named constants can be meaningfully combined.
An enumeration is a value type that defines a set of related named constants. By default, the System.Int32 data type is used to store the constant value. Although you can change this underlying type, it is not required or recommended for most scenarios.
This rule detects methods that have names that ordinarily would be used for events. If a method is called in response to a clearly defined state change, the method should be invoked by an event handler. Objects that call the method should raise events instead of calling the method directly.
General exceptions should not be caught. Catch a more specific exception, or rethrow the general exception as the last statement in the catch block.
Failure to provide the full set of constructors can make it difficult to correctly handle exceptions.
An unsealed externally visible type provides an explicit method implementation of a public interface and does not provide an alternative externally visible method that has the same name.
A nested type is a type that is declared in the scope of another type. Nested types are useful to encapsulate private implementation details of the containing type. Used for this purpose, nested types should not be externally visible.
This rule requires ICollection implementations to provide strongly typed members so that users are not required to cast arguments to the Object type when they use the functionality that is provided by the interface. This rule assumes that the type that implements ICollection does so to manage a collection of instances of a type that is stronger than Object.
A public or protected type implements the System.IComparable interface. It does not override Object.Equals nor does it overload the language-specific operator for equality, inequality, less than, or greater than.
This rule requires IEnumerator implementations to also provide a strongly typed version of the Current property so that users are not required to cast the return value to the strong type when they use the functionality that is provided by the interface.
This rule requires IList implementations to provide strongly typed members so that users are not required to cast arguments to the System.Object type when they use the functionality that is provided by the interface.
Interfaces define members that provide a behavior or usage contract. The functionality that is described by the interface can be adopted by any type, regardless of where the type appears in the inheritance hierarchy. A type implements an interface by providing implementations for the members of the interface. An empty interface does not define any members; therefore, it does not define a contract that can be implemented.
A type or member is marked by using a System.ObsoleteAttribute attribute that does not have its ObsoleteAttribute.Message property specified. When a type or member that is marked by using ObsoleteAttribute is compiled, the Message property of the attribute is displayed. This gives the user information about the obsolete type or member.
Indexers (that is, indexed properties) should use integral or string types for the index. These types are typically used for indexing data structures and they increase the usability of the library. Use of the Object type should be restricted to those cases where the specific integral or string type cannot be specified at design time.
Although it is acceptable and often necessary to have a read-only property, the design guidelines prohibit the use of write-only properties. This is because letting a user set a value, and then preventing the user from viewing that value, does not provide any security. Also, without read access, the state of shared objects cannot be viewed, which limits their usefulness.
Passing types by reference (using out or ref) requires experience with pointers, understanding how value types and reference types differ, and handling methods that have multiple return values. Library architects who design for a general audience should not expect users to master working with out or ref parameters.
For reference types, the default implementation of the equality operator is almost always correct. By default, two references are equal only if they point to the same object.
Types declare protected members so that inheriting types can access or override the member. By definition, sealed types cannot be inherited, which means that protected methods on sealed types cannot be called.
Types declare methods as virtual so that inheriting types can override the implementation of the virtual method. By definition, a sealed type cannot be inherited. This makes a virtual method on a sealed type meaningless.
Types that allocate unmanaged resources should implement IDisposable to enable callers to release those resources on demand and to shorten the lifetimes of the objects that hold the resources.
Types are declared in namespaces to prevent name collisions and as a way to organize related types in an object hierarchy.
The primary use of a field should be as an implementation detail. Fields should be private or internal and should be exposed by using properties.
A public or protected type contains only static members and is not declared by using the sealed (C# Reference) (NotInheritable) modifier. A type that is not meant to be inherited should be marked by using the sealed modifier to prevent its use as a base type.
A public or nested public type declares only static members and has a public or protected default constructor. The constructor is unnecessary because calling static members does not require an instance of the type. The string overload should call the uniform resource identifier (URI) overload by using the string argument for safety and security.
If a method takes a string representation of a URI, a corresponding overload should be provided that takes an instance of the URI class, which provides these services in a safe and secure manner.
This rule assumes that the method returns a URI. A string representation of a URI is prone to parsing and encoding errors, and can lead to security vulnerabilities. The System.Uri class provides these services in a safe and secure manner.
This rule assumes that the property represents a Uniform Resource Identifier (URI). A string representation of a URI is prone to parsing and encoding errors, and can lead to security vulnerabilities. The System.Uri class provides these services in a safe and secure manner.
A type declares method overloads that differ only by the replacement of a string parameter with a System.Uri parameter. The overload that takes the string parameter does not call the overload that takes the URI parameter.
An externally visible type extends certain base types. Use one of the alternatives.
A concrete type is a type that has a complete implementation and therefore can be instantiated. To enable widespread use of the member, replace the concrete type by using the suggested interface.
Platform Invocation methods, such as those that are marked by using the System.Runtime.InteropServices.DllImportAttribute attribute, or methods that are defined by using the Declare keyword in Visual Basic, access unmanaged code. These methods should be of the NativeMethods, SafeNativeMethods, or UnsafeNativeMethods class.
A method in a base type is hidden by an identically named method in a derived type, when the parameter signature of the derived method differs only by types that are more weakly derived than the corresponding types in the parameter signature of the base method.
All reference arguments that are passed to externally visible methods should be checked against null.
All IDisposable types should implement the Dispose pattern correctly.
An internal exception is visible only inside its own internal scope. After the exception falls outside the internal scope, only the base exception can be used to catch the exception. If the internal exception is inherited from T:System.Exception, T:System.SystemException, or T:System.ApplicationException, the external code will not have sufficient information to know what to do with the exception.
A method that is not expected to throw exceptions throws an exception.
To correctly display a message box for cultures that use a right-to-left reading order, the RightAlign and RtlReading members of the MessageBoxOptions enumeration must be passed to the Show method.
An access key, also known as an accelerator, enables keyboard access to a control by using the ALT key. When multiple controls have duplicate access keys, the behavior of the access key is not well defined.
The System.Environment.SpecialFolder enumeration contains members that refer to special system folders. The locations of these folders can have different values on different operating systems; the user can change some of the locations; and the locations are localized. The Environment.GetFolderPath method returns the locations that are associated with the Environment.SpecialFolder enumeration, localized and appropriate for the currently running computer.
An externally visible method passes a string literal as a parameter to a constructor or method in the .NET Framework class library, and that string should be localizable.
A method or constructor calls a member that has an overload that accepts a System.Globalization.CultureInfo parameter, and the method or constructor does not call the overload that takes the CultureInfo parameter. When a CultureInfo or System.IFormatProvider object is not supplied, the default value that is supplied by the overloaded member might not have the effect that you want in all locales.
A method or constructor calls one or more members that have overloads that accept a System.IFormatProvider parameter, and the method or constructor does not call the overload that takes the IFormatProvider parameter. When a System.Globalization.CultureInfo or IFormatProvider object is not supplied, the default value that is supplied by the overloaded member might not have the effect that you want in all locales.
The locale determines culture-specific presentation elements for data, such as formatting that is used for numeric values, currency symbols, and sort order. When you create a DataTable or DataSet, you should explicitly set the locale.
A string comparison operation uses a method overload that does not set a StringComparison parameter.
Strings should be normalized to uppercase. A small group of characters cannot make a round trip when they are converted to lowercase.
A string comparison operation that is nonlinguistic does not set the StringComparison parameter to either Ordinal or OrdinalIgnoreCase. By explicitly setting the parameter to either StringComparison.Ordinal or StringComparison.OrdinalIgnoreCase, your code often gains speed, becomes more correct, and becomes more reliable.
A public or protected method is marked by using the System.Runtime.InteropServices.DllImportAttribute attribute. Either the unmanaged library could not be located or the method could not be matched to a function in the library.
A public or protected method in a public type has the System.Runtime.InteropServices.DllImportAttribute attribute (also implemented by the Declare keyword in Visual Basic). Such methods should not be exposed.
When overloaded methods are exposed to COM clients, only the first method overload retains its name. Subsequent overloads are uniquely renamed by appending to the name an underscore character (_) and an integer that corresponds to the order of declaration of the overload.
A COM-visible value type is marked by using the System.Runtime.InteropServices.StructLayoutAttribute attribute set to LayoutKind.Auto. The layout of these types can change between versions of the .NET Framework, which will break COM clients that expect a specific layout.
A call is made to the Marshal.GetLastWin32Error method or the equivalent Win32 GetLastError function, and the immediately previous call is not to an operating system invoke method.
A COM-visible type derives from a type that is not COM-visible.
Visual Basic 6 COM clients cannot access 64-bit integers.
COM does not support static methods.
Types that use a dual interface enable clients to bind to a specific interface layout. Any changes in a future version to the layout of the type or any base types will break COM clients that bind to the interface. By default, if the ClassInterfaceAttribute attribute is not specified, a dispatch-only interface is used.
A reference type that is specifically marked as visible to COM contains a public parameterized constructor but does not contain a public default (parameterless) constructor. A type without a public default constructor is not creatable by COM clients.
A type declares a method that is marked by using the System.Runtime.InteropServices.ComRegisterFunctionAttribute attribute but does not declare a method marked by using the System.Runtime.InteropServices.ComUnregisterFunctionAttribute attribute, or vice versa.
A method marked by using the System.Runtime.InteropServices.ComRegisterFunctionAttribute attribute or the System.Runtime.InteropServices.ComUnregisterFunctionAttribute attribute is externally visible.
A type is marked by using the System.Runtime.InteropServices.ComSourceInterfacesAttribute attribute, and at least one of the specified interfaces is not marked by using the System.Runtime.InteropServices.InterfaceTypeAttribute attribute set to ComInterfaceType.InterfaceIsIDispatch.
Nonpublic instance fields of COM-visible value types are visible to COM clients. Review the content of the fields for information that should not be exposed, or that will have unintended design or security effects.
The Boolean data type has multiple representations in unmanaged code.
This rule looks for operating system invoke method declarations that target Win32 functions that have a pointer to an OVERLAPPED structure parameter and the corresponding managed parameter is not a pointer to a System.Threading.NativeOverlapped structure.
An instance method declares a parameter or a local variable whose name matches an instance field of the declaring type, leading to errors.
A type is more than four levels deep in its inheritance hierarchy. Deeply nested type hierarchies can be difficult to follow, understand, and maintain.
This rule measures the number of linearly independent paths through the method, which is determined by the number and complexity of conditional branches.
The name of an instance field starts with "s_", or the name of a static (Shared in Visual Basic) field starts with "m_".
A type or method has a low maintainability index value. A low maintainability index indicates that a type or method is probably difficult to maintain and would be a good candidate for redesign.
This rule measures class coupling by counting the number of unique type references that a type or method contains.
Do not set process priority to Idle. Processes that have System.Diagnostics.ProcessPriorityClass.Idle will occupy the CPU when it would otherwise be idle, and will therefore block standby.
Higher-frequency periodic activity will keep the CPU busy and interfere with power-saving idle timers that turn off the display and hard disks.
This rule assumes that an enumeration member that has a name that contains "reserved" is not currently used but is a placeholder to be renamed or removed in a future version. Renaming or removing a member is a breaking change.
Each word in the resource string is split into tokens based on the casing. Each contiguous two-token combination is checked by the Microsoft spelling checker library. If recognized, the word produces a violation of the rule.
The name of an identifier contains multiple words, and at least one of the words appears to be a compound word that is not cased correctly.
A resource string contains one or more words that are not recognized by the Microsoft spelling checker library.
The name of an externally visible identifier contains one or more words that are not recognized by the Microsoft spelling checker library.
By convention, identifier names do not contain the underscore (_) character. This rule checks namespaces, types, members, and parameters.
Identifiers for namespaces, types, members, and parameters cannot differ only by case because languages that target the common language runtime are not required to be case-sensitive.
By convention, parameter names use camel casing and namespace, type, and member names use Pascal casing.
By convention, the names of types that extend certain base types or that implement certain interfaces, or types that are derived from these types, have a suffix that is associated with the base type or interface.
By convention, only the names of types that extend certain base types or that implement certain interfaces, or types that are derived from these types, should end with specific reserved suffixes. Other type names should not use these reserved suffixes.
Names of enumeration members are not prefixed by using the type name because development tools are expected to provide type information.
The name of an event starts with "Before" or "After". To name related events that are raised in a specific sequence, use the present or past tense to indicate the relative position in the sequence of actions.
A public enumeration has the System.FlagsAttribute attribute, and its name does not end in "s". Types that are marked by using FlagsAttribute have names that are plural because the attribute indicates that more than one value can be specified.
The name of an externally visible interface does not start with an uppercase "I". The name of a generic type parameter on an externally visible type or method does not start with an uppercase "T".
A namespace name or a type name matches a reserved keyword in a programming language. Identifiers for namespaces and types should not match keywords that are defined by languages that target the common language runtime.
Naming conventions dictate that a plural name for an enumeration indicates that more than one value of the enumeration can be specified at the same time.
A parameter name should communicate the meaning of a parameter and a member name should communicate the meaning of a member. It would be a rare design where these were the same. Naming a parameter the same as its member name is unintuitive and makes the library difficult to use.
The name of a parameter in an externally visible member contains a data type name, or the name of an externally visible member contains a language-specific data type name.
The name of a public or protected member starts with "Get" and otherwise matches the name of a public or protected property. "Get" methods and properties should have names that clearly distinguish their function.
By convention, only certain programming elements have names that begin with a specific prefix.
Type names should not match the names of namespaces that are defined in the .NET Framework class library. Violating this rule can reduce the usability of the library.
Consistent naming of parameters in an override hierarchy increases the usability of the method overrides. A parameter name in a derived method that differs from the name in the base declaration can cause confusion about whether the method is an override of the base method or a new overload of the method.
The name of an externally visible identifier includes a term for which an alternative, preferred term exists. Alternatively, the name includes the term "Flag" or "Flags".
Duplicate casts decrease performance, especially when the casts are performed in compact iteration statements.
A method signature includes a parameter that is not used in the method body.
A field is declared static and read-only (Shared and ReadOnly in Visual Basic), and is initialized by using a value that is computable at compile time. Because the value that is assigned to the targeted field is computable at compile time, change the declaration to a const (Const in Visual Basic) field so that the value is computed at compile time instead of at run time.
Unused local variables and unnecessary assignments increase the size of an assembly and decrease performance.
A new object is created but never used; or a method that creates and returns a new string is called and the new string is never used; or a COM or P/Invoke method returns an HRESULT or error code that is never used.
A common performance optimization is to store a value in a processor register instead of memory, which is referred to as "enregistering the value". To increase the chance that all local variables are enregistered, limit the number of local variables to 64.
When a type declares an explicit static constructor, the just-in-time (JIT) compiler adds a check to each static method and instance constructor of the type to make sure that the static constructor was previously called. Static constructor checks can decrease performance.
A private or internal (assembly-level) member does not have callers in the assembly; it is not invoked by the common language runtime; and it is not invoked by a delegate.
An instance of an assembly-level type is not created by code in the assembly.
The .NET Framework class library provides methods for retrieving custom attributes. By default, these methods search the attribute inheritance hierarchy. Sealing the attribute eliminates the search through the inheritance hierarchy and can improve performance.
A jagged array is an array whose elements are arrays. The arrays that make up the elements can be of different sizes, leading to less wasted space for some sets of data.
For value types, the inherited implementation of Equals uses the Reflection library and compares the contents of all fields. Reflection is computationally expensive, and comparing every field for equality might be unnecessary. If you expect users to compare or sort instances, or to use instances as hash table keys, your value type should implement Equals.
A method that is an implementation of Dispose does not call GC.SuppressFinalize; or a method that is not an implementation of Dispose calls GC.SuppressFinalize; or a method calls GC.SuppressFinalize and passes something other than this (Me in Visual Basic).
Arrays that are returned by properties are not write-protected, even when the property is read-only. To keep the array tamper-proof, the property must return a copy of the array. Typically, users will not understand the adverse performance implications of calling such a property.
Comparing strings by using the String.Length property or the String.IsNullOrEmpty method is significantly faster than using Equals.
Whenever you can, avoid finalizers because of the additional performance overhead that is involved in tracking object lifetime. An empty finalizer incurs added overhead and delivers no benefit.
Members that do not access instance data or call instance methods can be marked as static (Shared in Visual Basic). After you mark the methods as static, the compiler will emit nonvirtual call sites to these members. This can give you a measurable performance gain for performance-sensitive code.
Private fields were detected that do not appear to be accessed in the assembly.
The NeutralResourcesLanguage attribute informs the ResourceManager of the language that was used to display the resources of a neutral culture for an assembly. This improves lookup performance for the first resource that you load and can reduce your working set.
This rule checks that structures that are declared by using explicit layout will align correctly when marshaled to unmanaged code on 64-bit operating systems.
This rule evaluates the size of each parameter and the return value of a P/Invoke, and verifies that the size of the parameter is correct when marshaled to unmanaged code on 32-bit and 64-bit operating systems.
A member or type is using a member or type that was introduced in a service pack that was not included together with the targeted framework of the project.
Because an exceptional event might occur that will prevent the finalizer of an object from running, the object should be explicitly disposed before all references to it are out of scope.
A member calls a potentially dangerous or problematic method.
An object is said to have a weak identity when it can be directly accessed across application domain boundaries. A thread that tries to acquire a lock on an object that has a weak identity can be blocked by a second thread in a different application domain that has a lock on the same object.
A managed thread is being treated as a Win32 thread.
If you convert to SafeHandle usage, remove all calls to GC.KeepAlive (object). In this case, classes should not have to call GC.KeepAlive. This assumes they do not have a finalizer but rely on SafeHandle to finalize the OS handle for them.
Use of IntPtr in managed code might indicate a potential security and reliability problem. All uses of IntPtr must be reviewed to determine whether use of a SafeHandle, or similar technology, is required in its place.
A method sets the System.Data.IDbCommand.CommandText property by using a string that is built from a string argument to the method. This rule assumes that the string argument contains user input. A SQL command string that is built from user input is vulnerable to SQL injection attacks.
A platform invoke member allows partially trusted callers, has a string parameter, and does not explicitly marshal the string. This can cause a potential security vulnerability.
A member in an assembly that is not marked by using the RuntimeCompatibilityAttribute or is marked RuntimeCompatibility(WrapNonExceptionThrows = false) contains a catch block that handles System.Exception and does not contain an immediately following general catch block.
A method uses imperative security and might be constructing the permission by using state information or return values that can change as long as the demand is active. Use declarative security whenever possible.
An externally visible type contains an externally visible read-only field that is a mutable reference type. A mutable type is a type whose instance data can be modified.
When you apply the read-only (ReadOnly in Visual Basic) modifier to a field that contains an array, the field cannot be changed to reference a different array. However, the elements of the array that are stored in a read-only field can be changed.
A method asserts a permission and no security checks are performed on the caller. Asserting a security permission without performing any security checks can leave an exploitable security weakness in your code.
The PermitOnly method and CodeAccessPermission.Deny security actions should be used only by those who have an advanced knowledge of .NET Framework security. Code that uses these security actions should undergo a security review.
A public or protected value type is secured by Data Access or Link Demands.
A public or protected event-handling method was detected. Event-handling methods should not be exposed unless absolutely necessary.
A pointer is not private, internal, or read-only. Malicious code can change the value of the pointer, which potentially gives access to arbitrary locations in memory or causes application or system failures.
A public or protected type contains public fields and is secured by Link Demands. If code has access to an instance of a type that is secured by a link demand, the code does not have to satisfy the link demand to access the fields of the type.
A method should not have both method-level and type-level declarative security for the same action.
This rule detects errors that might occur because an unmanaged resource is being finalized while it is still being used in unmanaged code.
When the APTCA (AllowPartiallyTrustedCallersAttribute) is present on a fully trusted assembly, and the assembly executes code in another assembly that does not allow for partially trusted callers, a security exploit is possible.
When the APTCA is present on a fully trusted assembly, and a type in the assembly inherits from a type that does not allow for partially trusted callers, a security exploit is possible.
SuppressUnmanagedCodeSecurityAttribute changes the default security system behavior for members that execute unmanaged code that uses COM interop or operating system invocation. This attribute is primarily used to increase performance; however, the performance gains come together with significant security risks.
An inheritable public type provides an overridable method implementation of an internal (Friend in Visual Basic) interface. To fix a violation of this rule, prevent the method from being overridden outside the assembly.
This type has a constructor that takes a System.Runtime.Serialization.SerializationInfo object and a System.Runtime.Serialization.StreamingContext object (the signature of the serialization constructor). This constructor is not secured by a security check, but one or more of the regular constructors in the type are secured.
The system calls the static constructor before the first instance of the type is created or any static members are referenced. If a static constructor is not private, it can be called by code other than the system. Depending on the operations that are performed in the constructor, this can cause unexpected behavior.
A public or protected member has Link Demands and is called by a member that does not perform any security checks. A link demand checks the permissions of the immediate caller only.
This rule matches a method to its base method, which is either an interface or a virtual method in another type, and then compares the link demands on each. If this rule is violated, a malicious caller can bypass the link demand just by calling the unsecured method.
A public or protected method contains a try/finally block. The finally block appears to reset the security state and is not itself enclosed in a finally block.
A public unsealed type is protected by using a link demand and has an overridable method. Neither the type nor the method is protected by using an inheritance demand.
Critical code cannot occur in a 100 percent−transparent assembly. This rule analyzes 100 percent−transparent assemblies for any SecurityCritical annotations at the type, field, and method levels.
This rule analyzes all methods and types in an assembly that is either 100 percent−transparent or mixed transparent/critical, and flags any declarative or imperative use of Assert.
Methods that are marked by SecurityTransparentAttribute call nonpublic members that are marked as SecurityCritical. This rule analyzes all methods and types in an assembly that is mixed transparent/critical, and flags any calls from transparent code to nonpublic critical code that are not marked as SecurityTreatAsSafe.
Transparency enforcement is not enforced for constant values because compilers inline constant values so that no lookup is required at run time. Constant fields should be security transparent so that code reviewers do not assume that transparent code cannot access the constant.
A type participates in type equivalence and either the type itself, or a member or field of the type, is marked by using the SecurityCriticalAttribute attribute. This rule occurs on any critical types or types that contain critical methods or fields that are participating in type equivalence. When the CLR detects such a type, it does not load it with a TypeLoadException at run time. Typically, this rule is raised only when users implement type equivalence manually instead of in by relying on tlbimp and the compilers to do the type equivalence.
Types and members that have the SecurityCriticalAttribute cannot be used by Silverlight application code. Security-critical types and members can be used only by trusted code in the .NET Framework for Silverlight class library. Because a public or protected construction in a derived class must have the same or greater transparency than its base class, a class in an application cannot be derived from a class marked as SecurityCritical.
This warning is raised on a method that binds a delegate that is marked by using the SecurityCriticalAttribute to a method that is transparent or that is marked by using the SecuritySafeCriticalAttribute. The warning also is raised on a method that binds a delegate that is transparent or safe-critical to a critical method.
This rule is raised when a method marked by using the SecurityCriticalAttribute overrides a method that is transparent or marked by using the SecuritySafeCriticalAttribute. The rule also is raised when a method that is transparent or marked by using the SecuritySafeCriticalAttribute overrides a method that is marked by using a SecurityCriticalAttribute. The rule is applied when overriding a virtual method or implementing an interface.
LinkDemands are deprecated in the level 2 security rule set. Instead of using LinkDemands to enforce security at JIT compilation time, mark the methods, types, and fields by using the SecurityCriticalAttribute attribute.
Transparency attributes are applied from code elements of larger scope to elements of smaller scope. The transparency attributes of code elements that have larger scope take precedence over transparency attributes of code elements that are contained in the first element. For example, a class that is marked by using the SecurityCriticalAttribute attribute cannot contain a method that is marked by using the SecuritySafeCriticalAttribute attribute.
A method contains unverifiable code or returns a type by reference. This rule is raised on attempts by security transparent code to execute unverifiable microsoft intermediate language (MISL). However, the rule does not contain a full IL verifier, and instead uses heuristics to catch most violations of MSIL verification.
A security transparent method calls a method that is marked by using the SuppressUnmanagedCodeSecurityAttribute attribute.
This rule is raised by any method that is transparent and attempts to handle a process corrupting exception by using the HandleProcessCorruptedStateExceptionsAttribute attribute. A process corrupting exception is a CLR version 4.0 exception classification of exceptions such as AccessViolationException. The HandleProcessCorruptedStateExceptionsAttribute attribute may be used only by security critical methods, and will be ignored if it is applied to a transparent method.
A code element that is marked by using the SecurityCriticalAttribute attribute is security critical. A transparent method cannot use a security critical element. If a transparent type attempts to use a security critical type, a TypeAccessException, MethodAccessException, or FieldAccessException is raised.
A security transparent method calls a method in an assembly that is not marked by using the APTCA, or a security transparent method satisfies a LinkDemand for a type or a method.
This rule is raised on transparent methods that require LinkDemands to access them. Security transparent code should not be responsible for verifying the security of an operation, and therefore should not demand permissions.
Security transparent code should not be responsible for verifying the security of an operation, and therefore should not demand permissions. Security transparent code should use full demands to make security decisions and safe-critical code should not rely on transparent code to have made the full demand.
The security review for transparent code is not as complete as the security review for critical code because transparent code cannot perform security sensitive actions. Assemblies that are loaded from a byte array might not be noticed in transparent code, and that byte array might contain critical, or more important safe-critical code, that does have to be audited.
Methods that are decorated by the SuppressUnmanagedCodeSecurityAttribute attribute have an implicit LinkDemand put upon any method that calls it. This LinkDemand requires that the calling code be security critical. Marking the method that uses SuppressUnmanagedCodeSecurity by using the SecurityCriticalAttribute attribute makes this requirement more obvious for callers of the method.
This rule is raised when a derived type has a security transparency attribute that is not as critical as its base type or implemented interface. Only critical types can derive from critical base types or implement critical interfaces, and only critical or safe-critical types can derive from safe-critical base types or implement safe-critical interfaces.
Code that is marked as SecurityTransparentAttribute is not granted sufficient permissions to assert.
This rule is raised on any transparent method that calls directly into native code (for example, through a P/Invoke). Violations of this rule lead to a MethodAccessException in the level 2 transparency model and a full demand for UnmanagedCode in the level 1 transparency model.
An exception is rethrown and the exception is explicitly specified in the throw statement. If an exception is rethrown by specifying the exception in the throw statement, the list of method calls between the original method that threw the exception and the current method is lost.
This makes the original error difficult to detect and debug.
A method implementation contains code paths that could cause multiple calls to System.IDisposable.Dispose or a Dispose equivalent (such as a Close() method on some types) on the same object.
A literal string in a method body contains one or more words that are not recognized by the Microsoft spelling checker library.
An operating system invoke method is defined and a method that has the equivalent functionality is located in the .NET Framework class library.
A value type declares an explicit static constructor. To fix a violation of this rule, initialize all static data when it is declared and remove the static constructor.
A call is made to the default (parameterless) constructor of an exception type that is or derives from ArgumentException, or an incorrect string argument is passed to a parameterized constructor of an exception type that is or derives from ArgumentException.
The strong name protects clients from unknowingly loading an assembly that has been tampered with. Assemblies without strong names should not be deployed outside very limited scenarios. If you share or distribute assemblies that are not correctly signed, the assembly can be tampered with, the common language runtime might not load the assembly, or the user might have to disable verification on his or her computer.
Static fields that are neither constants nor read-only are not thread-safe. Access to such a field must be carefully controlled and requires advanced programming techniques to synchronize access to the class object.
A method in a type that inherits from System.EnterpriseServices.ServicedComponent is marked by using System.Web.Services.WebMethodAttribute. Because WebMethodAttribute and a ServicedComponent method have conflicting behavior and requirements for context and transaction flow, the behavior of the method will be incorrect in some scenarios.
A type that implements System.IDisposable declares fields that are of types that also implement IDisposable. The Dispose method of the field is not called by the Dispose method of the declaring type.
When a constructor calls a virtual method, the constructor for the instance that invokes the method may not have executed.
If a type inherits from a disposable type, it must call the Dispose method of the base type from its own Dispose method.
A type that implements System.IDisposable and has fields that suggest the use of unmanaged resources does not implement a finalizer, as described by Object.Finalize.
An externally visible enumeration is marked by using FlagsAttribute, and it has one or more values that are not powers of two or a combination of the other defined values on the enumeration.
GetHashCode returns a value, based on the current instance, that is suited for hashing algorithms and data structures such as a hash table. Two objects that are the same type and are equal must return the same hash code.
When an exception is raised in a finally or fault clause, the new exception hides the active exception. When an exception is raised in a filter clause, the run time silently catches the exception. This makes the original error difficult to detect and debug.
Finalization must be propagated through the inheritance hierarchy. To guarantee this, types must call their base class Finalize method in their own Finalize method.
Finalizers must use the family access modifier.
You should not change the access modifier for inherited members. Changing an inherited member to private does not prevent callers from accessing the base class implementation of the method.
Although the common language runtime allows the use of return types to differentiate between otherwise identical members, this feature is not in the Common Language Specification, nor is it a common feature of .NET programming languages.
A public type implements the equality operator but does not override Object.Equals.
An operator overload was detected, and the expected named alternative method was not found. The named alternative member provides access to the same functionality as the operator and is provided for developers who program in languages that do not support overloaded operators.
A type implements the equality or inequality operator and does not implement the opposite operator.
A writable collection property allows a user to replace the collection with a different collection. A read-only property stops the collection from being replaced but still allows the individual members to be set.
Resource files that were built by using prerelease versions of the .NET Framework might not be usable by supported versions of the .NET Framework.
To fix a violation of this rule, implement the serialization constructor. For a sealed class, make the constructor private; otherwise, make it protected.
A public or protected type contains a public or protected method that uses the VarArgs calling convention instead of the params keyword.
A value type overrides Object.Equals but does not implement the equality operator.
STAThreadAttribute indicates that the COM threading model for the application is a single-threaded apartment. This attribute must be present on the entry point of any application that uses Windows Forms; if it is omitted, the Windows components might not work correctly.
You should not perform arithmetic operations without first validating the operands. This makes sure that the result of the operation is not outside the range of possible values for the data types that are involved.
A call is made to a method that has a string parameter whose name contains "uri", "URI", "urn", "URN", "url", or "URL". The declaring type of the method contains a corresponding method overload that has a System.Uri parameter.
An instance field of a type that is not serializable is declared in a type that is serializable.
To fix a violation of this rule, call the base type GetObjectData method or serialization constructor from the corresponding derived type method or constructor.
To be recognized by the common language runtime as serializable, types must be marked by using the SerializableAttribute attribute even when the type uses a custom serialization routine through implementation of the ISerializable interface.
A method that handles a serialization event does not have the correct signature, return type, or visibility.
A type has a field that is marked by using the System.Runtime.Serialization.OptionalFieldAttribute attribute, and the type does not provide deserialization event handling methods.
To fix a violation of this rule, make the GetObjectData method visible and overridable, and make sure that all instance fields are included in the serialization process or explicitly marked by using the NonSerializedAttribute attribute.
The format argument that is passed to System.String.Format does not contain a format item that corresponds to each object argument, or vice versa.
This expression tests a value against Single.Nan or Double.Nan. Use Single.IsNan(Single) or Double.IsNan(Double) to test the value.
The string literal parameter of an attribute does not parse correctly for a URL, a GUID, or a version.