CWE WEAKNESSES  /  CWE-178

CWE-178

Improper Handling of Case Sensitivity

What it is

The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.

Improperly handled case sensitive data can lead to several possible consequences, including:- case-insensitive passwords reducing the size of the key space, making brute force attacks easier- bypassing filters or access controls using alternate names- multiple interpretation errors using alternate names.

Impact

Mitigations

• [Architecture and Design] Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
• [Implementation]Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.When performing input validation, consider all potentially relevant properties, including length, type of input, the full r
• [Implementation] 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.

Real-world CVE examples

• CVE-2000-0499 — Application server allows attackers to bypass execution of a jsp page and read the source code using an upper case JSP extension in the request.
• CVE-2000-0497 — The server is case sensitive, so filetype handlers treat .jsp and .JSP as different extensions. JSP source code may be read because .JSP defaults to the filetyp
• CVE-2000-0498 — The server is case sensitive, so filetype handlers treat .jsp and .JSP as different extensions. JSP source code may be read because .JSP defaults to the filetyp
• CVE-2001-0766 — A URL that contains some characters whose case is not matched by the server's filters may bypass access restrictions because the case-insensitive file system wi
• CVE-2001-0795 — Server allows remote attackers to obtain source code of CGI scripts via URLs that contain MS-DOS conventions such as (1) upper case letters or (2) 8.3 file name
• CVE-2001-1238 — Task Manager does not allow local users to end processes with uppercase letters named (1) winlogon.exe, (2) csrss.exe, (3) smss.exe and (4) services.exe via the
• CVE-2003-0411 — chain: Code was ported from a case-sensitive Unix platform to a case-insensitive Windows platform where filetype handlers treat .jsp and .JSP as different exten
• CVE-2002-0485 — Leads to interpretation error
• CVE-1999-0239 — Directories may be listed because lower case web requests are not properly handled by the server.
• CVE-2005-0269 — File extension check in forum software only verifies extensions that contain all lowercase letters, which allows remote attackers to upload arbitrary files via
• CVE-2004-1083 — Web server restricts access to files in a case sensitive manner, but the filesystem accesses files in a case insensitive manner, which allows remote attackers t
• CVE-2002-2119 — Case insensitive passwords lead to search space reduction.

Related weaknesses

Source: MITRE CWE. View on cwe.mitre.org →