CWE-33: Path Traversal: '....' (Multiple Dot)
Description
The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize '....' (multiple dot) sequences that can resolve to a location that is outside of that directory.
This allows attackers to traverse the file system to access files or directories that are outside of the restricted directory. The '....' manipulation is useful for bypassing some path traversal protection schemes. On some Windows systems, it is equivalent to ...... and might bypass checks that assume only two dots are valid. Incomplete filtering, such as removal of ./ sequences, can ultimately produce valid .. sequences due to a collapse into unsafe value (CWE-182).
- Abstraction
- VariantA weakness tied to a specific language, technology or resource.
- Likelihood of exploit
- Not rated by MITRE
- Status
- Incomplete
Common consequences
- ConfidentialityIntegrity
Read Files or Directories; Modify Files or Directories
Potential mitigations
- ImplementationInput ValidationEffectiveness: High
Assume all input is malicious. Use an accept known good input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, boat may be syntactically valid...
- ImplementationInput Validation
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.
Related weaknesses
Parent weaknesses
CAPEC attack patterns that exploit it
CWE 4.20 links no CAPEC attack pattern to this weakness.