Programs must comply with the principle of least privilege not only by providing privileged blocks with the minimum permissions required for correct operation (see 16. Avoid granting excess privileges) , but also by ensuring that privileged code contains only those operations that require increased privileges. Superfluous code contained within a privileged block must operate with the privileges of that block, increasing the attack surface.
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This example violates the principle of least privilege because an unprivileged caller could also cause the authentication library to be loaded. An unprivileged caller cannot invoke the System.loadLibrary() method directly , because this could expose native methods to the unprivileged code [SCG 2010]. Furthermore, the System.loadLibrary() method checks only the privileges of its immediate caller, so it should be used only with great care. For more information, see 18. Do not expose methods that use reduced-security checks to untrusted code.
Compliant Solution
This compliant solution moves the call to System.loadLibrary() outside the doPrivileged() block. Doing so allows unprivileged code to perform preliminary password - reset checks using the file , but prevents it from loading the authentication library.
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