CWE-273: Improper Check for Dropped Privileges
The product attempts to drop privileges but does not check or incorrectly checks to see if the drop succeeded.
How it's found
Improper Check for Dropped Privileges is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.
If the drop fails, the product will continue to run with the raised privileges, which might provide additional access to unprivileged users.
Consequences
- Gain Privileges or Assume Identity: If privileges are not dropped, neither are access rights of the user. Often these rights can be prevented from being dropped.
- Gain Privileges or Assume Identity, Hide Activities: If privileges are not dropped, in some cases the system may record actions as the user which is being impersonated rather than the impersonator.
Mitigations
- Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
- Implementation: Check the results of all functions that return a value and verify that the value is expected.
- Implementation: In Windows, make sure that the process token has the SeImpersonatePrivilege(Microsoft Server 2003). Code that relies on impersonation for security must ensure that the impersonation succeeded, i.e., that a proper privilege demotion happened.
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is CWE-273?
The product attempts to drop privileges but does not check or incorrectly checks to see if the drop succeeded.
How do you find Improper Check for Dropped Privileges?
Improper Check for Dropped Privileges is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.
What is the impact of CWE-273?
Gain Privileges or Assume Identity: If privileges are not dropped, neither are access rights of the user. Often these rights can be prevented from being dropped. Gain Privileges or Assume Identity, Hide Activities: If privileges are not dropped, in some cases the system may record actions as the user which is being impersonated rather than the impersonator.
Does TurboPentest test for Improper Check for Dropped Privileges?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Related CWEs
Written and reviewed by
Michel Chamberland - Founder & CEO, IntegSec
CISSP, OSCP, OSCE, CEH, GIAC, CCSK · 20+ years in offensive security
Michel has spent 20+ years on offensive security teams including IBM X-Force Red and Trustwave SpiderLabs, leading penetration tests, red team engagements, and breach response for Fortune 500 customers. He is the founder of IntegSec and the architect of TurboPentest.
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