CWE-271: Privilege Dropping / Lowering Errors
The product does not drop privileges before passing control of a resource to an actor that does not have those privileges.
How it's found
Privilege Dropping / Lowering Errors describes a general pattern rather than a single fixed bug. Testers use a mix of static analysis and manual code review to find where a target's code matches this pattern, then confirm exploitability by hand.
In some contexts, a system executing with elevated permissions will hand off a process/file/etc. to another process or user. If the privileges of an entity are not reduced, then elevated privileges are spread throughout a system and possibly to an attacker.
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.
- Architecture and Design/Operation: Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Architecture and Design: Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource.
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-271?
The product does not drop privileges before passing control of a resource to an actor that does not have those privileges.
How do you find Privilege Dropping / Lowering Errors?
Privilege Dropping / Lowering Errors describes a general pattern rather than a single fixed bug. Testers use a mix of static analysis and manual code review to find where a target's code matches this pattern, then confirm exploitability by hand.
What is the impact of CWE-271?
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 Privilege Dropping / Lowering Errors?
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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