CoSetProxyBlanket and CoInitializeSecurity both work to set the permissions context in which the process invoked immediately after is executed. Calling them from within that process is useless because it’s too late at that point; the permissions context has already been set.

Specifically, these methods are meant to be called from non-managed code such as a C++ wrapper that then invokes the managed, i.e. C# or VB.NET, code.

Noncompliant Code Example

[DllImport("ole32.dll")]
static extern int CoSetProxyBlanket([MarshalAs(UnmanagedType.IUnknown)]object pProxy, uint dwAuthnSvc, uint dwAuthzSvc,
	[MarshalAs(UnmanagedType.LPWStr)] string pServerPrincName, uint dwAuthnLevel, uint dwImpLevel, IntPtr pAuthInfo,
	uint dwCapabilities);

public enum RpcAuthnLevel
{
	Default = 0,
	None = 1,
	Connect = 2,
	Call = 3,
	Pkt = 4,
	PktIntegrity = 5,
	PktPrivacy = 6
}

public enum RpcImpLevel
{
	Default = 0,
	Anonymous = 1,
	Identify = 2,
	Impersonate = 3,
	Delegate = 4
}

public enum EoAuthnCap
{
	None = 0x00,
	MutualAuth = 0x01,
	StaticCloaking = 0x20,
	DynamicCloaking = 0x40,
	AnyAuthority = 0x80,
	MakeFullSIC = 0x100,
	Default = 0x800,
	SecureRefs = 0x02,
	AccessControl = 0x04,
	AppID = 0x08,
	Dynamic = 0x10,
	RequireFullSIC = 0x200,
	AutoImpersonate = 0x400,
	NoCustomMarshal = 0x2000,
	DisableAAA = 0x1000
}

[DllImport("ole32.dll")]
public static extern int CoInitializeSecurity(IntPtr pVoid, int cAuthSvc, IntPtr asAuthSvc, IntPtr pReserved1,
	RpcAuthnLevel level, RpcImpLevel impers, IntPtr pAuthList, EoAuthnCap dwCapabilities, IntPtr pReserved3);

static void Main(string[] args)
{
	var hres1 = CoSetProxyBlanket(null, 0, 0, null, 0, 0, IntPtr.Zero, 0); // Noncompliant

	var hres2 = CoInitializeSecurity(IntPtr.Zero, -1, IntPtr.Zero, IntPtr.Zero, RpcAuthnLevel.None,
		RpcImpLevel.Impersonate, IntPtr.Zero, EoAuthnCap.None, IntPtr.Zero); // Noncompliant
}

See