The product validates input before applying protection mechanisms that modify the input, which could allow an attacker to bypass the validation via dangerous inputs that only arise after the modification.
Product needs to validate data at the proper time, after data has been canonicalized and cleansed. Early validation is susceptible to various manipulations that result in dangerous inputs that are produced by canonicalization and cleansing.
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.
CVE: CVE-2002-0934
Directory traversal vulnerability allows remote attackers to read or modify arbitrary files via invalid characters between two . (dot) characters, which are filtered and result in a ".." sequence.
CVE: CVE-2003-0282
Directory traversal vulnerability allows attackers to overwrite arbitrary files via invalid characters between two . (dot) characters, which are filtered and result in a ".." sequence.
N/A
| Phase | Note |
|---|---|
| Implementation | Since early validation errors usually arise from improperly implemented defensive mechanisms, it is likely that these will be introduced more frequently as secure programming becomes implemented more widely. |
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(); }Intro: This script creates a subdirectory within a user directory and sets the user as the owner.
Body: While the script attempts to screen for '..' sequences, an attacker can submit a directory path including ".~.", which will then become ".." after the filtering step. This allows a Path Traversal (CWE-21) attack to occur.
function createDir($userName,$dirName){ $userDir = '/users/'. $userName; if(strpos($dirName,'..') !== false){ echo 'Directory name contains invalid sequence'; return; } //filter out '~' because other scripts identify user directories by this prefix $dirName = str_replace('~','',$dirName); $newDir = $userDir . $dirName; mkdir($newDir, 0700); chown($newDir,$userName); }