CVE-2020-29453: Atlassian Jira Path Traversal Flaw

CVE-2020-29453 Overview

CVE-2020-29453 is a path traversal vulnerability affecting Atlassian Jira Server and Jira Data Center. The CachingResourceDownloadRewriteRule class contains an incorrect path access check that allows unauthenticated remote attackers to read arbitrary files within the WEB-INF and META-INF directories. This vulnerability enables unauthorized access to sensitive configuration files and application metadata without requiring any authentication.

Critical Impact

Unauthenticated attackers can exploit this path traversal flaw to access sensitive configuration files, potentially exposing database credentials, API keys, and other critical application settings stored in Jira's internal directories.

Affected Products

• Atlassian Jira Server versions before 8.5.11
• Atlassian Jira Server and Data Center versions 8.6.0 to before 8.13.3
• Atlassian Jira Server and Data Center versions 8.14.0 to before 8.15.0

Discovery Timeline

• 2021-02-22 - CVE CVE-2020-29453 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-29453

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Path Traversal), a weakness that allows attackers to bypass access controls by manipulating file paths. The flaw resides in the CachingResourceDownloadRewriteRule class, which is responsible for handling resource download requests within Jira. Due to improper validation of user-supplied path input, attackers can craft malicious requests that traverse outside intended directories to access protected files within WEB-INF and META-INF folders.

The WEB-INF and META-INF directories in Java web applications typically contain critical configuration files such as web.xml, application properties, and potentially database connection strings. Unauthorized access to these files can provide attackers with valuable reconnaissance information for further attacks against the Jira installation or connected systems.

Root Cause

The root cause of this vulnerability is an incorrect path access check implementation within the CachingResourceDownloadRewriteRule class. The class fails to properly sanitize and validate file path inputs before processing resource download requests. This inadequate input validation allows specially crafted path sequences to bypass the intended access restrictions, enabling directory traversal attacks that reach protected application directories.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by sending specially crafted HTTP requests to a vulnerable Jira instance. The malicious request manipulates the file path parameter to traverse directories and access files within the restricted WEB-INF and META-INF directories. Since no authentication is required, any remote attacker with network access to the Jira server can potentially exploit this vulnerability to extract sensitive configuration data.

The exploitation involves crafting URL paths that include directory traversal sequences designed to bypass the flawed access check in the CachingResourceDownloadRewriteRule class. When the vulnerable component processes these requests, it inadvertently serves files from protected directories to the attacker. For detailed technical information, refer to the Atlassian security advisory JRASERVER-72014.

Detection Methods for CVE-2020-29453

Indicators of Compromise

• Unusual HTTP requests containing path traversal patterns targeting Jira resource endpoints
• Access log entries showing requests attempting to reach WEB-INF or META-INF directories
• Repeated requests from single IP addresses probing for sensitive configuration files
• Web server logs indicating successful retrieval of files like web.xml or application property files

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block path traversal patterns in HTTP requests
• Configure intrusion detection systems (IDS) to alert on requests containing ../, WEB-INF, or META-INF traversal attempts
• Enable detailed access logging on Jira instances and monitor for suspicious request patterns
• Deploy SentinelOne Singularity to detect exploitation attempts and anomalous file access behavior

Monitoring Recommendations

• Review Jira access logs regularly for requests targeting resource download endpoints with unusual path parameters
• Establish baseline behavior for Jira resource requests and alert on deviations
• Monitor network traffic for outbound connections following potential data exfiltration attempts
• Implement file integrity monitoring on Jira configuration directories to detect unauthorized access

How to Mitigate CVE-2020-29453

Immediate Actions Required

• Upgrade Atlassian Jira Server to version 8.5.11 or later for the 8.5.x branch
• Upgrade Atlassian Jira Server and Data Center to version 8.13.3 or later for the 8.6.x through 8.13.x branches
• Upgrade Atlassian Jira Server and Data Center to version 8.15.0 or later for the 8.14.x branch
• Implement network segmentation to limit access to Jira instances from untrusted networks

Patch Information

Atlassian has released security patches addressing this vulnerability in Jira Server and Data Center. Organizations should upgrade to the following fixed versions based on their current installation:

• Version 8.5.11 or later for systems on the 8.5.x release branch
• Version 8.13.3 or later for systems on versions 8.6.0 through 8.13.2
• Version 8.15.0 or later for systems on versions 8.14.0 through 8.14.x

For complete patch details and upgrade instructions, refer to the Atlassian Jira Issue JRASERVER-72014.

Workarounds

• Deploy a web application firewall (WAF) with rules to block path traversal attempts targeting Jira resource endpoints
• Restrict network access to Jira instances using firewall rules to limit exposure to trusted networks only
• Implement reverse proxy configurations that sanitize incoming requests and block directory traversal patterns
• Enable additional authentication layers such as VPN requirements for accessing Jira servers

# Example: Block path traversal patterns in Apache reverse proxy
# Add to Apache configuration for Jira reverse proxy
RewriteEngine On
RewriteCond %{REQUEST_URI} (\.\./)|(WEB-INF)|(META-INF) [NC]
RewriteRule .* - [F,L]