Improper Resolution of Path Equivalence

Description

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.

Extended Description

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.

Common Consequences 1

Scope: ConfidentialityIntegrityAccess Control

Impact: Read Files or DirectoriesModify Files or DirectoriesBypass 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.

Detection Methods 7

Automated Static Analysis - Binary or BytecodeSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Bytecode Weakness Analysis - including disassembler + source code weakness analysis

Manual Static Analysis - Binary or BytecodeSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Dynamic Analysis with Automated Results InterpretationSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Web Application Scanner Web Services Scanner Database Scanners

Dynamic Analysis with Manual Results InterpretationSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Fuzz Tester Framework-based Fuzzer

Manual Static Analysis - Source CodeHigh

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections)

Automated Static Analysis - Source CodeSOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer

Architecture or Design ReviewHigh

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Formal Methods / Correct-By-Construction ``` Cost effective for partial coverage: ``` Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Potential Mitigations 3

Phase: Implementation

Strategy: 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.

Phase: Implementation

Strategy: 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.

Phase: Implementation

Strategy: Input Validation

Inputs should be decoded and canonicalized to the application's current internal representation before being validated (Incorrect Behavior Order: Validate Before Canonicalize). Make sure that the application does not decode the same input twice (Double Decoding of the Same Data). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

Observed Examples 50

CVE-2000-1114Source code disclosure using trailing dot

CVE-2002-1986Source code disclosure using trailing dot

CVE-2004-2213Source code disclosure using trailing dot or trailing encoding space "%20"

CVE-2005-3293Source code disclosure using trailing dot

CVE-2004-0061Bypass directory access restrictions using trailing dot in URL

CVE-2000-1133Bypass directory access restrictions using trailing dot in URL

CVE-2001-1386Bypass check for ".lnk" extension using ".lnk."

CVE-2001-0693Source disclosure via trailing encoded space "%20"

CVE-2001-0778Source disclosure via trailing encoded space "%20"

CVE-2001-1248Source disclosure via trailing encoded space "%20"

CVE-2004-0280Source disclosure via trailing encoded space "%20"

CVE-2005-0622Source disclosure via trailing encoded space "%20"

CVE-2005-1656Source disclosure via trailing encoded space "%20"

CVE-2002-1603Source disclosure via trailing encoded space "%20"

CVE-2001-0054Multi-Factor Vulnerability (MFV). directory traversal and other issues in FTP server using Web encodings such as "%20"; certain manipulations have unusual side effects.

CVE-2002-1451Trailing space ("+" in query string) leads to source code disclosure.

CVE-2000-0293Filenames 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-2002-0253Overlaps infoleak

CVE-2001-0446Application server allows remote attackers to read source code for .jsp files by appending a / to the requested URL.

CVE-2004-0334Bypass Basic Authentication for files using trailing "/"

CVE-2001-0893Read sensitive files with trailing "/"

CVE-2001-0892Web server allows remote attackers to view sensitive files under the document root (such as .htpasswd) via a GET request with a trailing /.

CVE-2004-1814Directory traversal vulnerability in server allows remote attackers to read protected files via .. (dot dot) sequences in an HTTP request.

CVE-2002-1483Read files with full pathname using multiple internal slash.

CVE-1999-1456Server allows remote attackers to read arbitrary files via a GET request with more than one leading / (slash) character in the filename.

CVE-2004-0578Server allows remote attackers to read arbitrary files via leading slash (//) characters in a URL request.

CVE-2002-0275Server allows remote attackers to bypass authentication and read restricted files via an extra / (slash) in the requested URL.

CVE-2004-1032Product 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-2002-1238Server 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-2004-1878Product 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-2005-1365Server allows remote attackers to execute arbitrary commands via a URL with multiple leading "/" (slash) characters and ".." sequences.

CVE-2000-1050Access directory using multiple leading slash.

CVE-2001-1072Bypass access restrictions via multiple leading slash, which causes a regular expression to fail.

CVE-2004-0235Archive extracts to arbitrary files using multiple leading slash in filenames in the archive.

CVE-2002-1078Directory listings in web server using multiple trailing slash

CVE-2004-0847ASP.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), aka "Path Validation Vulnerability."

CVE-2000-0004Server allows remote attackers to read source code for executable files by inserting a . (dot) into the URL.

CVE-2002-0304Server allows remote attackers to read password-protected files via a /./ in the HTTP request.

CVE-1999-1083Possibly (could be a cleansing error)

CVE-2004-0815"/./////etc" cleansed to ".///etc" then "/etc"

CVE-2002-0112Server allows remote attackers to view password protected files via /./ in the URL.

CVE-2004-0696List directories using desired path and "*"

CVE-2002-0433List files in web server using "*.ext"

CVE-2001-1152Proxy 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-2000-0191application check access for restricted URL before canonicalization

CVE-2005-1366CGI source disclosure using "dirname/../cgi-bin"

CVE-1999-0012Multiple web servers allow restriction bypass using 8.3 names instead of long names

CVE-2001-0795Source code disclosure using 8.3 file name.

CVE-2005-0471Multi-Factor Vulnerability. Product generates temporary filenames using long filenames, which become predictable in 8.3 format.

References 1

State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation

Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, and Rama S. Moorthy

07-2014

https://www.ida.org/-/media/feature/publications/s/st/stateoftheart-resources-soar-for-software-vulnerability-detection-test-and-evaluation/p-5061.ashx(2025-09-05)

ID: REF-1479

Applicable Platforms

Languages:

Not Language-Specific : Undetermined

Modes of Introduction

Implementation

Related Attack Patterns

3
DEPRECATED: Technology-specific Environment Issues

Functional Areas

File Processing

Affected Resources

File or Directory

Related Weaknesses

ChildOf:

Use of Incorrectly-Resolved Name or Reference (CWE-706)

Taxonomy Mapping

PLOVER
CERT C Secure Coding

Notes

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