Path Equivalence: 'fakedir/../realdir/filename'

Opis

The product contains protection mechanisms to restrict access to 'realdir/filename', but it constructs pathnames using external input in the form of 'fakedir/../realdir/filename' that are not handled by those mechanisms. This allows attackers to perform unauthorized actions against the targeted file.

Skutki

• Confidentiality, Integrity

  Read Files or Directories; Modify Files or Directories

Zapobieganie

• Implementation · Input 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.

Przykłady podatności

• CVE-2001-1152 Proxy allows remote attackers to bypass denylist restrictions and connect to unauthorized web servers by modifying the requested URL, including (1) a // (double slash), (2) a /SUBDIR/.. where the desired file is in the parentdir, (3) a /./, or (4) URL-encoded characters.
• CVE-2000-0191 application check access for restricted URL before canonicalization
• CVE-2005-1366 CGI source disclosure using "dirname/../cgi-bin"

Słabość nadrzędna

• CWE-41 Improper Resolution of Path Equivalence

Kiedy powstaje

• Implementation

Dotyczy

Not Language-Specific, Not Technology-Specific

Uwagi

This is a manipulation that uses an injection for one consequence (containment violation using relative path) to achieve a different consequence (equivalence by alternate name).