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CWE-41: Improper Resolution of Path Equivalence

 
Improper Resolution of Path Equivalence
Weakness ID: 41 (Weakness Base)Status: Incomplete
+ Description

Description Summary

The system or application 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.

+ Time of Introduction
  • Implementation
+ Applicable Platforms

Languages

All

+ Common Consequences
ScopeEffect
Confidentiality
Integrity
Access Control

Technical Impact: 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.

+ Observed Examples
ReferenceDescription
CVE-2000-1114Source code disclosure using trailing dot
CVE-2002-1986,Source 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 (MVF). 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-2001-0446 Application 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.
BID:3518Source code disclosure
CVE-2002-1483Read 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-2000-1050Access 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-2004-0847 ASP.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-2000-0004 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.
BID:6042Input Validation error
CVE-1999-1083Possibly (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-2004-0696List directories using desired path and "*"
CVE-2002-0433List files in web server using "*.ext"
CVE-2001-1152 Proxy allows remote attackers to bypass blacklist 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.
+ Potential Mitigations

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a whitelist 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 (i.e., do not rely on a blacklist). A blacklist 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, blacklists 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 (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass whitelist validation schemes by introducing dangerous inputs after they have been checked.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfCategoryCategory21Pathname Traversal and Equivalence Errors
Development Concepts (primary)699
ChildOfCategoryCategory632Weaknesses that Affect Files or Directories
Resource-specific Weaknesses (primary)631
ChildOfWeakness ClassWeakness Class706Use of Incorrectly-Resolved Name or Reference
Research Concepts (primary)1000
ChildOfCategoryCategory723OWASP Top Ten 2004 Category A2 - Broken Access Control
Weaknesses in OWASP Top Ten (2004) (primary)711
ChildOfCategoryCategory743CERT C Secure Coding Section 09 - Input Output (FIO)
Weaknesses Addressed by the CERT C Secure Coding Standard (primary)734
ChildOfCategoryCategory877CERT C++ Secure Coding Section 09 - Input Output (FIO)
Weaknesses Addressed by the CERT C++ Secure Coding Standard (primary)868
ChildOfCategoryCategory893SFP Cluster: Path Resolution
Software Fault Pattern (SFP) Clusters (primary)888
ParentOfWeakness VariantWeakness Variant42Path Equivalence: 'filename.' (Trailing Dot)
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant44Path Equivalence: 'file.name' (Internal Dot)
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant46Path Equivalence: 'filename ' (Trailing Space)
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant47Path Equivalence: ' filename' (Leading Space)
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant48Path Equivalence: 'file name' (Internal Whitespace)
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant49Path Equivalence: 'filename/' (Trailing Slash)
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant50Path Equivalence: '//multiple/leading/slash'
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant51Path Equivalence: '/multiple//internal/slash'
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant52Path Equivalence: '/multiple/trailing/slash//'
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant53Path Equivalence: '\multiple\\internal\backslash'
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant54Path Equivalence: 'filedir\' (Trailing Backslash)
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant55Path Equivalence: '/./' (Single Dot Directory)
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant56Path Equivalence: 'filedir*' (Wildcard)
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant57Path Equivalence: 'fakedir/../realdir/filename'
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant58Path Equivalence: Windows 8.3 Filename
Development Concepts (primary)699
Research Concepts (primary)1000
MemberOfViewView884CWE Cross-section
CWE Cross-section (primary)884
CanFollowWeakness ClassWeakness Class20Improper Input Validation
Research Concepts1000
CanFollowWeakness ClassWeakness Class73External Control of File Name or Path
Research Concepts1000
CanFollowWeakness ClassWeakness Class172Encoding Error
Research Concepts1000
+ Relationship Notes

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

+ Affected Resources
  • File/Directory
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERPath Equivalence
CERT C Secure CodingFIO02-CCanonicalize path names originating from untrusted sources
CERT C++ Secure CodingFIO02-CPPCanonicalize path names originating from untrusted sources
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVERExternally Mined
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITREInternal
updated Relationships, Other_Notes, Taxonomy_Mappings, Type
2008-10-14CWE Content TeamMITREInternal
updated Description
2008-11-24CWE Content TeamMITREInternal
updated Relationships, Taxonomy_Mappings
2009-03-10CWE Content TeamMITREInternal
updated Relationships
2009-05-27CWE Content TeamMITREInternal
updated Name
2009-07-27CWE Content TeamMITREInternal
updated Potential_Mitigations
2011-03-29CWE Content TeamMITREInternal
updated Other_Notes, Potential_Mitigations, Relationship_Notes
2011-06-01CWE Content TeamMITREInternal
updated Common_Consequences
2011-09-13CWE Content TeamMITREInternal
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITREInternal
updated Common_Consequences, Observed_Examples, Relationships
2012-10-30CWE Content TeamMITREInternal
updated Potential_Mitigations
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Path Equivalence
2009-05-27Failure to Resolve Path Equivalence
Page Last Updated: February 18, 2014