CWE-55 – Path Equivalence: ‘/./’ (Single Dot Directory)

Description

A software system that accepts path input in the form of single dot directory exploit (‘/./’) without appropriate validation can lead to ambiguous path resolution and allow an attacker to traverse the file system to unintended locations or access arbitrary files.

Modes of Introduction:

– Implementation

Related Weaknesses

CWE-41

Consequences

Confidentiality, Integrity: Read Files or Directories, Modify Files or Directories

Potential Mitigations

Phase: Implementation

Description: 

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.

CVE References

• CVE-2000-0004
  • Server allows remote attackers to read source code for executable files by inserting a . (dot) into the URL.

• CVE-2002-0304
  • Server allows remote attackers to read password-protected files via a /./ in the HTTP request.

• BID:6042
  • Input Validation error

• CVE-1999-1083
  • Possibly (could be a cleansing error)

• CVE-2004-0815
  • “/./////etc” cleansed to “.///etc” then “/etc”

• CVE-2002-0112
  • Server allows remote attackers to view password protected files via /./ in the URL.