Description

The software 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 software 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.

Many functions will return some value about the success of their actions. This will alert the program whether or not to handle any errors caused by that function.

Modes of Introduction:

– Implementation

Likelihood of Exploit: Low

Related Weaknesses

CWE-754
CWE-754
CWE-476

Consequences

Availability, Integrity: Unexpected State, DoS: Crash, Exit, or Restart

An unexpected return value could place the system in a state that could lead to a crash or other unintended behaviors.

Potential Mitigations

Phase: Implementation

Effectiveness: High

Description: 

Check the results of all functions that return a value and verify that the value is expected.

Checking the return value of the function will typically be sufficient, however beware of race conditions (CWE-362) in a concurrent environment.

Phase: Implementation

Description: 

Ensure that you account for all possible return values from the function.

Phase: Implementation

Description: 

When designing a function, make sure you return a value or throw an exception in case of an error.

CVE References

• CVE-2020-17533
  • Chain: unchecked return value (CWE-252) of some functions for policy enforcement leads to authorization bypass (CWE-862)

• CVE-2020-6078
  • Chain: 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-2019-15900
  • Chain: 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-2007-3798
  • Unchecked return value leads to resultant integer overflow and code execution.

• CVE-2006-4447
  • Program 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.

• CVE-2006-2916
  • Program 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.

• CVE-2008-5183
  • chain: unchecked return value can lead to NULL dereference

• CVE-2010-0211
  • chain: unchecked return value (CWE-252) leads to free of invalid, uninitialized pointer (CWE-824).

• CVE-2017-6964
  • Linux-based device mapper encryption program does not check the return value of setuid and setgid allowing attackers to execute code with unintended privileges.