Incorrect Behavior Order: Validate Before Canonicalize

Opis

The product validates input before it is canonicalized, which prevents the product from detecting data that becomes invalid after the canonicalization step.

This can be used by an attacker to bypass the validation and launch attacks that expose weaknesses that would otherwise be prevented, such as injection.

Skutki

• Access Control

  Bypass Protection Mechanism

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-2002-0433 List files in web server using "*.ext"
• CVE-2003-0332 Product modifies the first two letters of a filename extension after performing a security check, which allows remote attackers to bypass authentication via a filename with a .ats extension instead of a .hts extension.
• CVE-2002-0802 Database consumes an extra character when processing a character that cannot be converted, which could remove an escape character from the query and make the application subject to SQL injection attacks.
• CVE-2000-0191 Overlaps "fakechild/../realchild"
• CVE-2004-2363 Product checks URI for "<" and other literal characters, but does it before hex decoding the URI, so "%3E" and other sequences are allowed.

Słabość nadrzędna

• CWE-179 Incorrect Behavior Order: Early Validation

Słabości podrzędne

• CWE-647 Use of Non-Canonical URL Paths for Authorization Decisions

Kiedy powstaje

• Implementation

Dotyczy

Not Language-Specific

Uwagi

This overlaps other categories.