CVE-2024-21687: Atlassian Bamboo Path Traversal Flaw

CVE-2024-21687 Overview

CVE-2024-21687 is a Local File Inclusion (LFI) vulnerability affecting Atlassian Bamboo Data Center and Server. This vulnerability allows an authenticated attacker to manipulate the application into displaying the contents of local files or executing different files already stored on the server. The flaw poses significant risks to enterprise CI/CD environments, potentially exposing sensitive configuration data, credentials, and enabling further exploitation through the execution of malicious files present on the system.

Critical Impact

Authenticated attackers can read arbitrary local files and execute existing server-side files, leading to potential credential theft, configuration exposure, and lateral movement within affected environments.

Affected Products

• Atlassian Bamboo Data Center and Server version 9.0.0
• Atlassian Bamboo Data Center and Server versions 9.1.0, 9.2.0, 9.3.0, 9.4.0, 9.5.0
• Atlassian Bamboo Data Center and Server version 9.6.0

Discovery Timeline

• 2024-07-16 - CVE-2024-21687 published to NVD
• 2025-03-14 - Last updated in NVD database

Technical Details for CVE-2024-21687

Vulnerability Analysis

This File Inclusion vulnerability (CWE-98) enables authenticated attackers to exploit improper input validation in Bamboo's file handling mechanisms. When successfully exploited, attackers can force the application to include and display contents of local files that should not be accessible through the web interface. Additionally, the vulnerability allows execution of files already present on the server, which could include uploaded malicious scripts or leveraged system utilities.

The attack requires network access and valid authentication credentials but does not require user interaction. The impact is substantial for both confidentiality and integrity: attackers can read sensitive files such as configuration files, database credentials, API keys, and application secrets. The ability to execute existing local files compounds the risk, potentially allowing attackers to leverage uploaded content or existing system utilities for further compromise.

Root Cause

The vulnerability stems from insufficient validation and sanitization of file path parameters within Bamboo's request handling logic. The application fails to properly restrict file paths, allowing authenticated users to traverse directories or reference files outside the intended scope. This lack of proper input validation enables path manipulation techniques to access arbitrary local files on the server's filesystem.

Attack Vector

The attack is executed over the network against Bamboo Data Center and Server instances. An authenticated attacker crafts malicious requests containing specially formatted file path parameters designed to bypass directory restrictions. The attacker can manipulate these parameters to reference files outside the application's intended file access scope.

The vulnerability does not require elevated privileges beyond standard user authentication, making any authenticated Bamboo user a potential threat actor. Common exploitation scenarios include reading sensitive configuration files such as atlassian-user.xml, database connection strings, or environment configuration files. Attackers may also attempt to execute scripts or utilities already present on the server to establish persistent access or escalate privileges.

Detection Methods for CVE-2024-21687

Indicators of Compromise

• Unusual file access patterns in Bamboo server logs, particularly requests containing path traversal sequences like ../ or absolute file paths
• Authentication logs showing successful logins followed by abnormal file-related API calls
• Web server access logs containing encoded path traversal attempts (%2e%2e%2f, %252e%252e%252f)
• Unexpected file read operations in application logs referencing system files like /etc/passwd, configuration files, or credential stores

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block path traversal patterns in HTTP requests
• Configure SIEM alerts for Bamboo server events involving file inclusion or suspicious file path references
• Monitor for authenticated users accessing files outside of normal build artifact directories
• Deploy endpoint detection and response (EDR) solutions to identify anomalous file access patterns on Bamboo servers

Monitoring Recommendations

• Enable verbose logging for Bamboo Data Center and Server to capture detailed request parameters
• Configure centralized log aggregation for Bamboo instances with real-time alerting on suspicious patterns
• Implement file integrity monitoring (FIM) on sensitive server directories to detect unauthorized reads
• Establish baseline user behavior profiles to identify anomalous file access activities

How to Mitigate CVE-2024-21687

Immediate Actions Required

• Upgrade Atlassian Bamboo Data Center and Server to the latest patched version immediately
• Review authentication logs for any suspicious activity from authenticated users
• Audit existing user accounts and remove unnecessary or inactive accounts to reduce attack surface
• Implement network segmentation to limit access to Bamboo servers from untrusted networks

Patch Information

Atlassian has released security updates to address this vulnerability. Organizations should upgrade to the latest version of Bamboo Data Center and Server as recommended in the Atlassian Security Advisory. Specific fixed versions are documented in the advisory and the Bamboo Release Notes. The latest versions can be obtained from the Atlassian Download Center.

For tracking purposes, this issue is documented in Atlassian Jira Ticket BAM-25822.

Workarounds

• Restrict network access to Bamboo servers using firewall rules to allow only trusted IP ranges
• Implement additional authentication controls such as multi-factor authentication (MFA) for all Bamboo users
• Deploy a reverse proxy with strict URL filtering to block path traversal patterns before they reach Bamboo
• Conduct regular access reviews to ensure only necessary personnel have Bamboo authentication credentials

# Example: Restrict Bamboo server access using iptables
# Allow only specific trusted networks to access Bamboo
iptables -A INPUT -p tcp --dport 8085 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8085 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8085 -j DROP