CVE-2006-3119 in fbi
Summary
by MITRE
The fbgs framebuffer Postscript/PDF viewer in fbi before 2.01 has a typo that prevents a filter from working correctly, which allows user-assisted attackers to bypass the filter and execute malicious Postscript commands.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/24/2019
The vulnerability identified as CVE-2006-3119 resides within the fbgs framebuffer Postscript/PDF viewer component of the fbi package prior to version 2.01. This flaw represents a critical security issue that undermines the intended filtering mechanisms designed to prevent execution of potentially harmful Postscript commands. The vulnerability manifests through a simple yet impactful typo in the codebase that directly compromises the integrity of the security controls implemented to protect against malicious input.
The technical implementation of this vulnerability stems from a typographical error in the filtering logic that governs Postscript command execution within the fbgs framebuffer viewer. When processing Postscript documents, the system should properly validate and sanitize commands before execution, but the typo causes the filter to fail in its validation routine. This failure creates a direct pathway for attackers to inject malicious Postscript code that would normally be rejected by the filtering mechanism. The vulnerability operates at the application layer and specifically affects systems that rely on the fbgs component for viewing Postscript and PDF documents through framebuffer interfaces.
From an operational perspective, this vulnerability presents a significant risk to systems that process untrusted Postscript content, particularly in environments where users may have the ability to upload or access documents from external sources. The user-assisted nature of the attack means that an attacker must convince a victim to open a specially crafted document, but once executed, the malicious Postscript commands can potentially exploit the underlying system. This vulnerability aligns with CWE-1004 which addresses the issue of security-relevant code flaws in the context of filter implementation failures. The attack vector operates through the standard document viewing workflow where legitimate users inadvertently trigger the execution of malicious code.
The security implications extend beyond simple command execution as the vulnerability can potentially be leveraged for privilege escalation or system compromise depending on the execution environment. Systems running vulnerable versions of fbi with fbgs framebuffer support become susceptible to remote code execution through carefully crafted Postscript documents. This vulnerability demonstrates the critical importance of proper input validation and the potential consequences of seemingly minor coding errors in security-critical components. Organizations should consider implementing additional security controls such as mandatory document sanitization, restricted user permissions for document viewing, and regular security updates to protect against this and similar vulnerabilities.
Mitigation strategies should focus on immediate patching of affected systems to version 2.01 or later of the fbi package where the typo has been corrected. Network administrators should also consider implementing content filtering solutions that can detect and block potentially malicious Postscript documents before they reach end-user systems. The vulnerability highlights the necessity of thorough code review processes and automated testing procedures that can catch such typographical errors before deployment. Security teams should also establish monitoring protocols to detect unusual document processing activities that might indicate exploitation attempts. This vulnerability serves as a reminder of the critical role that code quality assurance plays in maintaining secure system environments and demonstrates how simple human errors in development can create significant security risks. The ATT&CK framework categorizes this vulnerability under the T1068 technique for 'Exploitation for Privilege Escalation' when the malicious Postscript commands can be leveraged to gain elevated system privileges through the vulnerable application.