CVE-2017-14589 in Bamboo
Summary
by MITRE
It was possible for double OGNL evaluation in FreeMarker templates through Struts FreeMarker tags to occur. An attacker who has restricted administration rights to Bamboo or who hosts a website that a Bamboo administrator visits, is able to exploit this vulnerability to execute Java code of their choice on systems that run a vulnerable version of Bamboo. All versions of Bamboo before 6.1.6 (the fixed version for 6.1.x) and from 6.2.0 before 6.2.5 (the fixed version for 6.2.x) are affected by this vulnerability.
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Analysis
by VulDB Data Team • 01/27/2021
This vulnerability represents a critical server-side template injection flaw in Atlassian Bamboo that leverages the FreeMarker templating engine's OGNL (Object-Graph Navigation Language) evaluation mechanism. The vulnerability arises from improper handling of user-supplied input within Struts FreeMarker tags, creating a condition where malicious OGNL expressions can be executed multiple times during template processing. The flaw specifically affects versions of Bamboo prior to 6.1.6 and 6.2.5, making it a widespread issue across multiple release branches that required immediate remediation. The vulnerability classification aligns with CWE-94, which describes "Improper Control of Generation of Code" and specifically addresses the execution of arbitrary code due to insecure template processing.
The technical exploitation of this vulnerability occurs through a double OGNL evaluation process where an attacker can inject malicious OGNL expressions that are processed twice, allowing for code execution on the target system. This occurs when a Bamboo administrator visits a malicious website or when an attacker has access to restricted administrative functions within Bamboo. The attack vector demonstrates the dangerous intersection of template injection and privilege escalation, as it allows an attacker with minimal administrative access to escalate privileges and execute arbitrary Java code. The vulnerability's impact is particularly severe because it enables remote code execution without requiring authentication to the Bamboo system itself, making it a prime target for attackers seeking persistent access to build servers.
The operational implications of this vulnerability extend beyond simple code execution, as it can enable complete system compromise of Bamboo servers that are not properly patched. Organizations running vulnerable versions of Bamboo face significant risk of data breaches, system takeover, and potential lateral movement within their infrastructure. The vulnerability affects the core build and deployment functionality of Bamboo, potentially allowing attackers to access source code repositories, steal build artifacts, and manipulate continuous integration pipelines. This makes the vulnerability particularly dangerous in enterprise environments where Bamboo is used for critical software delivery processes. The attack requires minimal privileges to exploit, making it especially concerning for organizations that grant administrative access to multiple users.
Mitigation strategies for this vulnerability include immediate patching to versions 6.1.6 or 6.2.5, depending on the affected release branch. Organizations should also implement network segmentation to limit access to Bamboo servers, enforce strict access controls, and monitor for suspicious template usage patterns. Security teams should conduct comprehensive vulnerability assessments of their Bamboo installations and review all user permissions to minimize the attack surface. The remediation process should include disabling unnecessary template features and implementing input validation controls to prevent malicious OGNL expressions from reaching the template engine. Additionally, organizations should consider implementing web application firewalls and runtime application self-protection mechanisms to detect and prevent exploitation attempts. This vulnerability demonstrates the critical importance of proper template security controls and input sanitization in enterprise applications, particularly those handling user-supplied content in build and deployment environments.