BaseIncompleteCWE-273

CWE-273: Improper Check for Dropped Privileges

Description

The product attempts to drop privileges but does not check or incorrectly checks to see if the drop succeeded.

If the drop fails, the product will continue to run with the raised privileges, which might provide additional access to unprivileged users.

Abstraction: BaseA weakness specific enough to point to detection and prevention methods.
Likelihood of exploit: Medium
Status: Incomplete

Common consequences

Access Control
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.
Access ControlNon-Repudiation
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.

Potential mitigations

Architecture and DesignSeparation of Privilege
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.
ImplementationEffectiveness: High
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.

Related weaknesses

Parent weaknesses

Peers

CWE-252Unchecked Return Value

CAPEC attack patterns that exploit it

CWE 4.20 links no CAPEC attack pattern to this weakness.

Common consequences

Access Control

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.

Access ControlNon-Repudiation

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.

Potential mitigations

Architecture and DesignSeparation of Privilege

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.

ImplementationEffectiveness: High

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.