According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Compare binary / bytecode to application permission manifest
CWE-272 Base Incomplete
Least Privilege Violation
This vulnerability occurs when software fails to reduce its elevated system privileges after completing a sensitive operation, leaving it with unnecessary and dangerous access rights.
Definition
What is CWE-272?
This vulnerability occurs when software fails to reduce its elevated system privileges after completing a sensitive operation, leaving it with unnecessary and dangerous access rights.
Many critical system functions, like changing the root directory with `chroot()`, require temporary high-level privileges. The secure pattern is to request these elevated rights, perform the single specific task, and then immediately and deliberately drop back down to a normal, restricted privilege level. Failing to do this creates a prolonged attack window where any subsequent bug or compromise in the software can be exploited with those high privileges, leading to severe system damage.
For developers, this means your code should follow a 'need-to-know' and 'need-to-use' principle for permissions. Structure your program to operate with the least privilege possible by default, escalate only for discrete operations, and revert immediately. This practice, often called privilege dropping or shedding, is a core defense-in-depth strategy that limits the potential impact of other security flaws in your application.
Real-world impact
Real-world CVEs caused by CWE-272
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 1
The following example demonstrates the weakness.
- 2
The following example demonstrates the weakness.
- 3
The following code calls chroot() to restrict the application to a subset of the filesystem below APP_HOME in order to prevent an attacker from using the program to gain unauthorized access to files located elsewhere. The code then opens a file specified by the user and processes the contents of the file.
- 4
Constraining the process inside the application's home directory before opening any files is a valuable security measure. However, the absence of a call to setuid() with some non-zero value means the application is continuing to operate with unnecessary root privileges. Any successful exploit carried out by an attacker against the application can now result in a privilege escalation attack because any malicious operations will be performed with the privileges of the superuser. If the application drops to the privilege level of a non-root user, the potential for damage is substantially reduced.
Vulnerable code example
Vulnerable C
The following example demonstrates the weakness.
setuid(0);
```
// Do some important stuff*
setuid(old_uid);
*// Do some non privileged stuff.* Secure code example
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-272
- Architecture and Design / Operation Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Architecture and Design Follow the principle of least privilege when assigning access rights to entities in a software system.
- 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.
Detection signals
How to detect CWE-272
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Host-based Vulnerability Scanners - Examine configuration for flaws, verifying that audit mechanisms work, ensure host configuration meets certain predefined criteria
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Manual Source Code Review (not inspections) ``` Cost effective for partial coverage: ``` Focused Manual Spotcheck - Focused manual analysis of source
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Permission Manifest Analysis
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Formal Methods / Correct-By-Construction ``` Cost effective for partial coverage: ``` Attack Modeling
CWE-272
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Frequently asked questions What is CWE-272?
How serious is CWE-272?
What languages or platforms are affected by CWE-272?
How can I prevent CWE-272?
How does Plexicus detect and fix CWE-272?
Where can I learn more about CWE-272?
Frequently asked questions
What is CWE-272?
This vulnerability occurs when software fails to reduce its elevated system privileges after completing a sensitive operation, leaving it with unnecessary and dangerous access rights.
How serious is CWE-272?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-272?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-272?
Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software. Follow the principle of least privilege when assigning access rights to entities in a software system.
How does Plexicus detect and fix CWE-272?
Plexicus's SAST engine matches the data-flow signature for CWE-272 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-272?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/272.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-272
CWE-271 Parent
Privilege Dropping / Lowering Errors
This vulnerability occurs when a system or process fails to reduce its elevated permissions before transferring control of a resource to a…
CWE-273 Sibling
Improper Check for Dropped Privileges
This vulnerability occurs when an application tries to lower its system privileges but fails to verify that the operation was successful.
Resources
Further reading
- MITRE — official CWE-272 https://cwe.mitre.org/data/definitions/272.html
- Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf
- State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation https://www.ida.org/-/media/feature/publications/s/st/stateoftheart-resources-soar-for-software-vulnerability-detection-test-and-evaluation/p-5061.ashx
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