CWE-59 Detail

CWE-59

Improper Link Resolution Before File Access ('Link Following')
Medium
Draft
2006-07-19
00h00 +00:00
2023-06-29
00h00 +00:00
CWE Mitre.org
Notifications for a CWE
Stay informed of any changes for a specific CWE.
Notifications manage

Name: Improper Link Resolution Before File Access ('Link Following')

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

General Informations

Background Details

Soft links are a UNIX term that is synonymous with simple shortcuts on Windows-based platforms.

Modes Of Introduction

Implementation : REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Language

Class: Not Language-Specific (Undetermined)

Operating Systems

Class: Windows (Sometimes)
Class: Unix (Often)

Common Consequences

Scope Impact Likelihood
Confidentiality
Integrity
Access Control		Read Files or Directories, Modify Files or Directories, Bypass Protection Mechanism

Note: 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 then an attacker may be able to bypass the mechanism.
OtherExecute Unauthorized Code or Commands

Note: Windows simple shortcuts, sometimes referred to as soft links, can be exploited remotely since a ".LNK" file can be uploaded like a normal file. This can enable remote execution.

Observed Examples

References Description

CVE-1999-1386

Some versions of Perl follow symbolic links when running with the -e option, which allows local users to overwrite arbitrary files via a symlink attack.

CVE-2000-1178

Text editor follows symbolic links when creating a rescue copy during an abnormal exit, which allows local users to overwrite the files of other users.

CVE-2004-0217

Antivirus update allows local users to create or append to arbitrary files via a symlink attack on a logfile.

CVE-2003-0517

Symlink attack allows local users to overwrite files.

CVE-2004-0689

Window manager does not properly handle when certain symbolic links point to "stale" locations, which could allow local users to create or truncate arbitrary files.

CVE-2005-1879

Second-order symlink vulnerabilities

CVE-2005-1880

Second-order symlink vulnerabilities

CVE-2005-1916

Symlink in Python program

CVE-2000-0972

Setuid product allows file reading by replacing a file being edited with a symlink to the targeted file, leaking the result in error messages when parsing fails.

CVE-2005-0824

Signal causes a dump that follows symlinks.

CVE-2001-1494

Hard link attack, file overwrite; interesting because program checks against soft links

CVE-2002-0793

Hard link and possibly symbolic link following vulnerabilities in embedded operating system allow local users to overwrite arbitrary files.

CVE-2003-0578

Server creates hard links and unlinks files as root, which allows local users to gain privileges by deleting and overwriting arbitrary files.

CVE-1999-0783

Operating system allows local users to conduct a denial of service by creating a hard link from a device special file to a file on an NFS file system.

CVE-2004-1603

Web hosting manager follows hard links, which allows local users to read or modify arbitrary files.

CVE-2004-1901

Package listing system allows local users to overwrite arbitrary files via a hard link attack on the lockfiles.

CVE-2005-1111

Hard link race condition

CVE-2000-0342

Mail client allows remote attackers to bypass the user warning for executable attachments such as .exe, .com, and .bat by using a .lnk file that refers to the attachment, aka "Stealth Attachment."

CVE-2001-1042

FTP server allows remote attackers to read arbitrary files and directories by uploading a .lnk (link) file that points to the target file.

CVE-2001-1043

FTP server allows remote attackers to read arbitrary files and directories by uploading a .lnk (link) file that points to the target file.

CVE-2005-0587

Browser allows remote malicious web sites to overwrite arbitrary files by tricking the user into downloading a .LNK (link) file twice, which overwrites the file that was referenced in the first .LNK file.

CVE-2001-1386

".LNK." - .LNK with trailing dot

CVE-2003-1233

Rootkits can bypass file access restrictions to Windows kernel directories using NtCreateSymbolicLinkObject function to create symbolic link

CVE-2002-0725

File system allows local attackers to hide file usage activities via a hard link to the target file, which causes the link to be recorded in the audit trail instead of the target file.

CVE-2003-0844

Web server plugin allows local users to overwrite arbitrary files via a symlink attack on predictable temporary filenames.

CVE-2015-3629

A Libcontainer used in Docker Engine allows local users to escape containerization and write to an arbitrary file on the host system via a symlink attack in an image when respawning a container.

CVE-2021-21272

"Zip Slip" vulnerability in Go-based Open Container Initiative (OCI) registries product allows writing arbitrary files outside intended directory via symbolic links or hard links in a gzipped tarball.

CVE-2020-27833

"Zip Slip" vulnerability in container management product allows writing arbitrary files outside intended directory via a container image (.tar format) with filenames that are symbolic links that point to other files within the same tar file; however, the files being pointed to can also be symbolic links to destinations outside the intended directory, bypassing the initial check.

Potential Mitigations

Phases : Architecture and Design

Follow the principle of least privilege when assigning access rights to entities in a software system.

Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.


Detection Methods

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness : SOAR Partial

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Effectiveness : SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness : SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Fuzz Tester
  • Framework-based Fuzzer

Effectiveness : SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Focused Manual Spotcheck - Focused manual analysis of source
  • Manual Source Code Review (not inspections)

Effectiveness : High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness : SOAR Partial

Architecture or Design Review

According to SOAR, 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.)

Effectiveness : High

Vulnerability Mapping Notes

Justification : This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comment : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Related Attack Patterns

CAPEC-ID Attack Pattern Name
CAPEC-132 Symlink Attack
An adversary positions a symbolic link in such a manner that the targeted user or application accesses the link's endpoint, assuming that it is accessing a file with the link's name.
CAPEC-17 Using Malicious Files
An attack of this type exploits a system's configuration that allows an adversary to either directly access an executable file, for example through shell access; or in a possible worst case allows an adversary to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface.
CAPEC-35 Leverage Executable Code in Non-Executable Files
An attack of this type exploits a system's trust in configuration and resource files. When the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high.
CAPEC-76 Manipulating Web Input to File System Calls
An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.

NotesNotes

Link following vulnerabilities are Multi-factor Vulnerabilities (MFV). They are the combination of multiple elements: file or directory permissions, filename predictability, race conditions, and in some cases, a design limitation in which there is no mechanism for performing atomic file creation operations.

Some potential factors are race conditions, permissions, and predictability.


References

REF-62

The Art of Software Security Assessment
Mark Dowd, John McDonald, Justin Schuh.

REF-1282

Zip Slip Vulnerability
Snyk.
https://security.snyk.io/research/zip-slip-vulnerability

Submission

Name Organization Date Date release Version
PLOVER 2006-07-19 +00:00 2006-07-19 +00:00 Draft 3

Modifications

Name Organization Date Comment
Eric Dalci Cigital 2008-07-01 +00:00 updated Time_of_Introduction
CWE Content Team MITRE 2008-09-08 +00:00 updated Alternate_Terms, Applicable_Platforms, Relationships, Other_Notes, Relationship_Notes, Taxonomy_Mappings, Weakness_Ordinalities
CWE Content Team MITRE 2008-11-24 +00:00 updated Relationships, Taxonomy_Mappings
CWE Content Team MITRE 2009-01-12 +00:00 updated Relationships
CWE Content Team MITRE 2009-05-27 +00:00 updated Description, Name
CWE Content Team MITRE 2009-10-29 +00:00 updated Background_Details, Other_Notes
CWE Content Team MITRE 2010-02-16 +00:00 updated Potential_Mitigations, Relationships
CWE Content Team MITRE 2010-04-05 +00:00 updated Related_Attack_Patterns
CWE Content Team MITRE 2011-06-01 +00:00 updated Common_Consequences
CWE Content Team MITRE 2011-09-13 +00:00 updated Relationships, Taxonomy_Mappings
CWE Content Team MITRE 2012-05-11 +00:00 updated Common_Consequences, Observed_Examples, References, Relationships
CWE Content Team MITRE 2012-10-30 +00:00 updated Potential_Mitigations
CWE Content Team MITRE 2014-06-23 +00:00 updated Common_Consequences, Other_Notes
CWE Content Team MITRE 2014-07-30 +00:00 updated Detection_Factors, Relationships, Taxonomy_Mappings
CWE Content Team MITRE 2015-12-07 +00:00 updated Relationships
CWE Content Team MITRE 2017-11-08 +00:00 updated Affected_Resources, Applicable_Platforms, Causal_Nature, Common_Consequences, Functional_Areas, Likelihood_of_Exploit, Modes_of_Introduction, Relationships, Taxonomy_Mappings
CWE Content Team MITRE 2019-01-03 +00:00 updated Taxonomy_Mappings
CWE Content Team MITRE 2019-06-20 +00:00 updated Relationships
CWE Content Team MITRE 2020-02-24 +00:00 updated Relationships
CWE Content Team MITRE 2021-03-15 +00:00 updated Relationships
CWE Content Team MITRE 2021-10-28 +00:00 updated Relationships
CWE Content Team MITRE 2022-04-28 +00:00 updated Research_Gaps
CWE Content Team MITRE 2022-06-28 +00:00 updated Relationships
CWE Content Team MITRE 2022-10-13 +00:00 updated Alternate_Terms, Background_Details, Observed_Examples, References, Relationship_Notes, Theoretical_Notes
CWE Content Team MITRE 2023-01-31 +00:00 updated Description
CWE Content Team MITRE 2023-04-27 +00:00 updated Relationships
CWE Content Team MITRE 2023-06-29 +00:00 updated Mapping_Notes
The information presented on CVE Find originates from several carefully selected reference sources. CVE data is provided by MITRE Corporation and the National Vulnerability Database (NVD). The Known Exploited Vulnerabilities (KEV) catalog is sourced from the Cybersecurity and Infrastructure Security Agency (CISA), while EPSS scores come from FIRST.org. Additionally, data regarding software weaknesses (CWE) and common attack patterns (CAPEC) is maintained by MITRE Corporation, and information on hardware and software configurations (CPE) is provided by the NVD.