CWE-41: Improper Resolution of Path Equivalence | Glexia
CWE-41 (Improper Resolution of Path Equivalence) weakness overview with consequences, detection methods, mitigations, related CVEs and MITRE ATT&CK context.
Glexia's Take · Automated analysis
CWE-41: Improper Resolution of Path Equivalence
Improper Resolution of Path Equivalence represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Confidentiality,Integrity,Access Control: Read Files or Directories,Modify Files or Directories,Bypass Protection Mechanism: An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism than an attacker may be able to bypass the mechanism.
Developer Pattern
CWE-41 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Automation confidence
high confidence from CWE-41, 4.20.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Official CWE Definition
CWE-41: Improper Resolution of Path Equivalence
The product is vulnerable to file system contents disclosure through path equivalence. Path equivalence involves the use of special characters in file and directory names. The associated manipulations are intended to generate multiple names for the same object.
Path equivalence is usually employed in order to circumvent access controls expressed using an incomplete set of file name or file path representations. This is different from path traversal, wherein the manipulations are performed to generate a name for a different object.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- Missing validation
- Unsafe defaults
- Insufficient authorization or memory-safety invariant
Remediation
- Implementation: Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
- Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
Detection
- Code review
- SAST
- DAST
- Focused regression tests
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
- CWE-1289: Improper Validation of Unsafe Equivalence in Input
- CWE-172: Encoding Error
- CWE-20: Improper Input Validation
- CWE-1390: Weak Authentication
- CWE-706: Use of Incorrectly-Resolved Name or Reference
- CWE-863: Incorrect Authorization
- CWE-42: Path Equivalence: 'filename.' (Trailing Dot)
- CWE-44: Path Equivalence: 'file.name' (Internal Dot)
- CWE-46: Path Equivalence: 'filename ' (Trailing Space)
- CWE-47: Path Equivalence: ' filename' (Leading Space)
- CWE-48: Path Equivalence: 'file name' (Internal Whitespace)
- CWE-49: Path Equivalence: 'filename/' (Trailing Slash)
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.