Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
Home > CWE List > CWE- Individual Dictionary Definition (3.0)  

CWE-273: Improper Check for Dropped Privileges

Weakness ID: 273
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The software attempts to drop privileges but does not check or incorrectly checks to see if the drop succeeded.
+ Extended Description
If the drop fails, the software will continue to run with the raised privileges, which might provide additional access to unprivileged users.
+ Relationships

The table(s) below shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

+ Relevant to the view "Research Concepts" (CWE-1000)
+ Relevant to the view "Architectural Concepts" (CWE-1008)
MemberOfCategoryCategory1011Authorize Actors
+ Relevant to the view "Development Concepts" (CWE-699)
ChildOfClassClass271Privilege Dropping / Lowering Errors
+ Background Details
In Windows based environments that have access control, impersonation is used so that access checks can be performed on a client identity by a server with higher privileges. By impersonating the client, the server is restricted to client-level security -- although in different threads it may have much higher privileges.
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

Architecture and Design

REALIZATION: This weakness is caused during implementation of an architectural security tactic.


This issue is likely to occur in restrictive environments in which the operating system or application provides fine-grained control over privilege management.

+ Applicable Platforms
The listings below show possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.


Class: Language-Independent (Undetermined Prevalence)

+ Common Consequences

The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

Access Control

Technical Impact: 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 Control

Technical Impact: 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.
+ Likelihood Of Exploit
+ Demonstrative Examples

Example 1

This code attempts to take on the privileges of a user before creating a file, thus avoiding performing the action with unnecessarily high privileges:

(bad code)
Example Language: C++ 
bool DoSecureStuff(HANDLE hPipe) {
bool fDataWritten = false;
HANDLE hFile = CreateFile(...);


The call to ImpersonateNamedPipeClient may fail, but the return value is not checked. If the call fails, the code may execute with higher privileges than intended. In this case, an attacker could exploit this behavior to write a file to a location that the attacker does not have access to.

+ Observed Examples
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.
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.
+ Potential Mitigations

Phase: Architecture and Design

Strategy: Separation 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 that the compartmentalization serves to allow for and further reinforce privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide when it is appropriate to use and to drop system privileges.

Phase: Implementation

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

Effectiveness: High

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

Phase: 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.
+ Weakness Ordinalities
(where the weakness exists independent of other weaknesses)
+ Affected Resources
  • System Process
+ Memberships
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CLASPFailure to check whether privileges were dropped successfully
CERT C Secure CodingPOS37-CExactEnsure that privilege relinquishment is successful
Software Fault PatternsSFP4Unchecked Status Condition
+ Content History
Submission DateSubmitterOrganization
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Common_Consequences, Description, Modes_of_Introduction, Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-03-10CWE Content TeamMITRE
updated Description, Name, Relationships
2009-05-27CWE Content TeamMITRE
updated Name
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Observed_Examples, Relationships
2012-10-30CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations
2014-06-23CWE Content TeamMITRE
updated Background_Details, Other_Notes, Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Causal_Nature, Demonstrative_Examples, Modes_of_Introduction, Relationships, Taxonomy_Mappings
Previous Entry Names
Change DatePrevious Entry Name
2009-03-10Failure to Check Whether Privileges Were Dropped Successfully
2009-05-27Improper Check for Successfully Dropped Privileges

More information is available — Please select a different filter.
Page Last Updated: January 18, 2018