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.
Threat Mapped score: 0.0
Industry: Finiancial
Threat priority: Unclassified
CVE: CVE-2002-0433
Product allows remote attackers to view restricted files via an HTTP request containing a "*" (wildcard or asterisk) character.
CVE: 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: 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: CVE-2000-0191
Overlaps "fakechild/../realchild"
CVE: 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.
| Phase | Note |
|---|---|
| Implementation | N/A |
Intro: The following code attempts to validate a given input path by checking it against an allowlist and then return the canonical path. In this specific case, the path is considered valid if it starts with the string "/safe_dir/".
Body: The problem with the above code is that the validation step occurs before canonicalization occurs. An attacker could provide an input path of "/safe_dir/../" that would pass the validation step. However, the canonicalization process sees the double dot as a traversal to the parent directory and hence when canonicized the path would become just "/".
String path = getInputPath(); if (path.startsWith("/safe_dir/")) { File f = new File(path); return f.getCanonicalPath(); }