Early Access — Mondoo Vulnerability Intelligence is currently in preview.
The product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.
Two common programmer assumptions are "this function call can never fail" and "it doesn't matter if this function call fails". If an attacker can force the function to fail or otherwise return a value that is not expected, then the subsequent program logic could lead to a vulnerability, because the product is not in a state that the programmer assumes. For example, if the program calls a function to drop privileges but does not check the return code to ensure that privileges were successfully dropped, then the program will continue to operate with the higher privileges.
Check the results of all functions that return a value and verify that the value is expected.
For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished [REF-1484].
Ensure that you account for all possible return values from the function.
When designing a function, make sure you return a value or throw an exception in case of an error.
An unexpected return value could place the system in a state that could lead to a crash or other unintended behaviors.
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CVE-2020-17533Chain: unchecked return value (CWE-252) of some functions for policy enforcement leads to authorization bypass (CWE-862)
CVE-2020-6078Chain: The return value of a function returning a pointer is not checked for success (CWE-252) resulting in the later use of an uninitialized variable (CWE-456) and a null pointer dereference (CWE-476)
CVE-2019-15900Chain: sscanf() call is used to check if a username and group exists, but the return value of sscanf() call is not checked (CWE-252), causing an uninitialized variable to be checked (CWE-457), returning success to allow authorization bypass for executing a privileged (CWE-863).
CVE-2007-3798Unchecked return value leads to resultant integer overflow and code execution.
CVE-2006-4447Program does not check return value when invoking functions to drop privileges, which could leave users with higher privileges than expected by forcing those functions to fail.