Improper Resolution of Path Equivalence

Opis

The product is vulnerable to file system contents disclosure through path equivalence. Path equivalence involves the use of special characters in file and directory names. The associated manipulations are intended to generate multiple names for the same object.

Path equivalence is usually employed in order to circumvent access controls expressed using an incomplete set of file name or file path representations. This is different from path traversal, wherein the manipulations are performed to generate a name for a different object.

Skutki

• Confidentiality, Integrity, Access Control

  Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism

  An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism than an attacker may be able to bypass the mechanism.

Zapobieganie

• Implementation · Input Validation

  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 range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

  Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

• Implementation · Output Encoding

  Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.

• 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-2000-1114 Source code disclosure using trailing dot
• CVE-2002-1986 Source code disclosure using trailing dot
• CVE-2004-2213 Source code disclosure using trailing dot or trailing encoding space "%20"
• CVE-2005-3293 Source code disclosure using trailing dot
• CVE-2004-0061 Bypass directory access restrictions using trailing dot in URL
• CVE-2000-1133 Bypass directory access restrictions using trailing dot in URL
• CVE-2001-1386 Bypass check for ".lnk" extension using ".lnk."
• CVE-2001-0693 Source disclosure via trailing encoded space "%20"
• CVE-2001-0778 Source disclosure via trailing encoded space "%20"
• CVE-2001-1248 Source disclosure via trailing encoded space "%20"
• CVE-2004-0280 Source disclosure via trailing encoded space "%20"
• CVE-2005-0622 Source disclosure via trailing encoded space "%20"
• CVE-2005-1656 Source disclosure via trailing encoded space "%20"
• CVE-2002-1603 Source disclosure via trailing encoded space "%20"
• CVE-2001-0054 Multi-Factor Vulnerability (MFV). directory traversal and other issues in FTP server using Web encodings such as "%20"; certain manipulations have unusual side effects.
• CVE-2002-1451 Trailing space ("+" in query string) leads to source code disclosure.
• CVE-2000-0293 Filenames with spaces allow arbitrary file deletion when the product does not properly quote them; some overlap with path traversal.
• CVE-2001-1567 "+" characters in query string converted to spaces before sensitive file/extension (internal space), leading to bypass of access restrictions to the file.
• CVE-2002-0253 Overlaps infoleak
• CVE-2001-0446 Application server allows remote attackers to read source code for .jsp files by appending a / to the requested URL.
• CVE-2004-0334 Bypass Basic Authentication for files using trailing "/"
• CVE-2001-0893 Read sensitive files with trailing "/"
• CVE-2001-0892 Web server allows remote attackers to view sensitive files under the document root (such as .htpasswd) via a GET request with a trailing /.
• CVE-2004-1814 Directory traversal vulnerability in server allows remote attackers to read protected files via .. (dot dot) sequences in an HTTP request.
• CVE-2002-1483 Read files with full pathname using multiple internal slash.
• CVE-1999-1456 Server allows remote attackers to read arbitrary files via a GET request with more than one leading / (slash) character in the filename.
• CVE-2004-0578 Server allows remote attackers to read arbitrary files via leading slash (//) characters in a URL request.
• CVE-2002-0275 Server allows remote attackers to bypass authentication and read restricted files via an extra / (slash) in the requested URL.
• CVE-2004-1032 Product allows local users to delete arbitrary files or create arbitrary empty files via a target filename with a large number of leading slash (/) characters.
• CVE-2002-1238 Server allows remote attackers to bypass access restrictions for files via an HTTP request with a sequence of multiple / (slash) characters such as http://www.example.com///file/.
• CVE-2004-1878 Product allows remote attackers to bypass authentication, obtain sensitive information, or gain access via a direct request to admin/user.pl preceded by // (double leading slash).
• CVE-2005-1365 Server allows remote attackers to execute arbitrary commands via a URL with multiple leading "/" (slash) characters and ".." sequences.
• CVE-2000-1050 Access directory using multiple leading slash.
• CVE-2001-1072 Bypass access restrictions via multiple leading slash, which causes a regular expression to fail.
• CVE-2004-0235 Archive extracts to arbitrary files using multiple leading slash in filenames in the archive.
• CVE-2002-1078 Directory listings in web server using multiple trailing slash
• CVE-2004-0847 web framework for .NET allows remote attackers to bypass authentication for .aspx files in restricted directories via a request containing a (1) "\" (backslash) or (2) "%5C" (encoded backslash)
• CVE-2000-0004 Server allows remote attackers to read source code for executable files by inserting a . (dot) into the URL.
• CVE-2002-0304 Server allows remote attackers to read password-protected files via a /./ in the HTTP request.
• CVE-1999-1083 Possibly (could be a cleansing error)
• CVE-2004-0815 "/./////etc" cleansed to ".///etc" then "/etc"
• CVE-2002-0112 Server allows remote attackers to view password protected files via /./ in the URL.
• CVE-2004-0696 List directories using desired path and "*"
• CVE-2002-0433 List files in web server using "*.ext"
• 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"
• CVE-1999-0012 Multiple web servers allow restriction bypass using 8.3 names instead of long names
• CVE-2001-0795 Source code disclosure using 8.3 file name.
• CVE-2005-0471 Multi-Factor Vulnerability. Product generates temporary filenames using long filenames, which become predictable in 8.3 format.

Słabość nadrzędna

• CWE-706 Use of Incorrectly-Resolved Name or Reference
• CWE-863 Incorrect Authorization
• CWE-1390 Weak Authentication

Słabości podrzędne

• CWE-42 Path Equivalence: 'filename.' (Trailing Dot)
• CWE-44 Path Equivalence: 'file.name' (Internal Dot)
• CWE-46 Path Equivalence: 'filename ' (Trailing Space)
• CWE-47 Path Equivalence: ' filename' (Leading Space)
• CWE-48 Path Equivalence: 'file name' (Internal Whitespace)
• CWE-49 Path Equivalence: 'filename/' (Trailing Slash)
• CWE-50 Path Equivalence: '//multiple/leading/slash'
• CWE-51 Path Equivalence: '/multiple//internal/slash'
• CWE-52 Path Equivalence: '/multiple/trailing/slash//'
• CWE-53 Path Equivalence: '\multiple\\internal\backslash'
• CWE-54 Path Equivalence: 'filedir\' (Trailing Backslash)
• CWE-55 Path Equivalence: '/./' (Single Dot Directory)
• CWE-56 Path Equivalence: 'filedir*' (Wildcard)
• CWE-57 Path Equivalence: 'fakedir/../realdir/filename'
• CWE-58 Path Equivalence: Windows 8.3 Filename

Kiedy powstaje

• Implementation

Dotyczy

Not Language-Specific

Uwagi

Some of these manipulations could be effective in path traversal issues, too.

Źródła

1. State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation — Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, Rama S. Moorthy, 2014