CVE-2013-4796 in ReviewBoard
Summary
by MITRE
ReviewBoard 1.6.17 allows code execution by attaching PHP scripts to review request
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Analysis
by VulDB Data Team • 03/18/2024
The vulnerability identified as CVE-2013-4796 represents a critical security flaw in ReviewBoard version 1.6.17 that enables remote code execution through improper input validation and file handling mechanisms. This issue stems from the application's insufficient sanitization of file attachments, particularly when users upload PHP scripts as part of review requests. The vulnerability creates an attack vector where malicious actors can exploit the review board's file attachment functionality to execute arbitrary code on the server hosting the application. The flaw specifically manifests when the system processes PHP files attached to review requests without adequate validation of file types or content, allowing attackers to upload malicious scripts that get executed within the web server context.
The technical implementation of this vulnerability involves the application's failure to properly validate file extensions and content when processing attachments. When a user uploads a file, the system should verify that the file type matches the expected format and that the content does not contain executable code. However, in ReviewBoard 1.6.17, the application accepts PHP files without proper scrutiny, and when these files are accessed through the web interface, they are executed as PHP scripts rather than being treated as static content. This behavior aligns with CWE-434, which describes the weakness of allowing files to be uploaded or saved to a location where they can be executed as code. The vulnerability is particularly dangerous because it leverages the legitimate file attachment feature of the review board, making it difficult to detect and distinguish from normal user activity.
The operational impact of this vulnerability extends beyond simple code execution to encompass full system compromise and potential data breaches. An attacker who successfully exploits this vulnerability can gain unauthorized access to the server hosting ReviewBoard, potentially leading to privilege escalation, data exfiltration, and persistent backdoor installation. The attack surface is broad since ReviewBoard is commonly used in development environments where attackers may already have some level of access or can exploit other initial compromise vectors. This vulnerability can be exploited through social engineering tactics where attackers convince users to upload malicious files, or through automated scanning tools that target known vulnerable versions. The exploitability factor is high due to the lack of authentication requirements for the attachment feature and the default configuration of many installations.
Mitigation strategies for CVE-2013-4796 should focus on immediate patching of the ReviewBoard application to version 1.6.18 or later, which contains the necessary security fixes. Organizations should implement strict file validation policies that prevent the upload of PHP files and other potentially executable content, while also configuring proper file type restrictions at the web server level. Network segmentation and access controls should be implemented to limit the potential impact of successful exploitation, and monitoring should be enhanced to detect unusual file upload patterns. Security measures should include implementing web application firewalls that can detect and block malicious file uploads, as well as regular security assessments of the application's file handling mechanisms. The vulnerability demonstrates the importance of following secure coding practices such as input validation and output encoding, which are fundamental principles in the OWASP Top Ten and align with ATT&CK technique T1059.007 for executing malicious code through web shells or file uploads. Organizations should also consider implementing automated patch management systems to ensure timely updates and reduce the window of exposure to known vulnerabilities.