CVE-2011-10018 in MyBB
Summary
by MITRE • 08/14/2025
myBB version 1.6.4 was distributed with an unauthorized backdoor embedded in the source code. The backdoor allowed remote attackers to execute arbitrary PHP code by injecting payloads into a specially crafted collapsed cookie. This vulnerability was introduced during packaging and was not part of the intended application logic. Exploitation requires no authentication and results in full compromise of the web server under the context of the web application.
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Analysis
by VulDB Data Team • 08/15/2025
The vulnerability identified as CVE-2011-10018 represents a critical supply chain compromise affecting myBB version 1.6.4, where an unauthorized backdoor was intentionally embedded within the application source code during the packaging process. This backdoor represents a sophisticated attack vector that fundamentally undermines the integrity of the software distribution mechanism and constitutes a severe deviation from standard software development practices. The backdoor was not present in the original source code but was introduced during the build process, making it particularly dangerous as it bypasses normal security controls and code review processes that would typically catch such malicious modifications.
The technical implementation of this backdoor relies on cookie manipulation as the primary attack vector, specifically targeting the collapsed cookie functionality within the myBB application. Attackers could inject malicious PHP code payloads through carefully crafted cookie values that would be executed in the context of the web server process. This exploitation mechanism operates at the application level and leverages the inherent trust relationships within the web application framework, making it particularly stealthy and difficult to detect through conventional security monitoring. The vulnerability falls under CWE-94, which describes "Improper Control of Generation of Code" and specifically relates to the execution of arbitrary code due to improper handling of user-supplied input. The attack requires no authentication credentials, making it extremely dangerous as it can be exploited by anyone with access to the target system.
The operational impact of this vulnerability is catastrophic for any system running the compromised myBB version, as it provides attackers with full remote code execution capabilities without requiring any authentication. This level of access enables attackers to perform complete system compromise including data exfiltration, privilege escalation, and establishment of persistent access points. The vulnerability affects the web application's execution context, allowing attackers to execute code with the same privileges as the web server process, which typically has access to database credentials, file system resources, and potentially network access to other systems within the infrastructure. This represents a direct violation of the principle of least privilege and provides attackers with a powerful foothold for further exploitation activities.
The introduction of this backdoor during the packaging phase highlights significant gaps in software supply chain security and quality assurance processes. Organizations should implement comprehensive code integrity verification mechanisms, including cryptographic signatures, checksum validation, and regular security audits of third-party software components. Mitigation strategies should include immediate patching of affected systems, implementation of network monitoring to detect suspicious cookie traffic patterns, and deployment of web application firewalls to block known malicious payloads. From an ATT&CK framework perspective, this vulnerability maps to techniques involving T1059.007 for command and scripting interpreter and T1566 for malicious file execution, while also demonstrating the importance of T1525 for exploitation of software vulnerabilities. System administrators should also conduct thorough security assessments of all installed software to identify potential backdoors and establish robust incident response procedures to address such supply chain compromises effectively.