CVE-2012-5006 in DjVu Browser Plug-in
Summary
by MITRE
Heap-based buffer overflow in npdjvu.dll in Caminova DjVu Browser Plug-in 6.1.4 Build 27351 and other versions before 6.1.4.27993 allows remote attackers to execute arbitrary code via a crafted Sjbz chunk in a djvu file.
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Analysis
by VulDB Data Team • 02/05/2018
The vulnerability identified as CVE-2012-5006 represents a critical heap-based buffer overflow affecting the npdjvu.dll component within Caminova DjVu Browser Plug-in versions prior to 6.1.4.27993. This flaw resides in the plugin's handling of Sjbz chunks within djvu files, creating a remote code execution vector that can be exploited by attackers who craft maliciously formatted files. The vulnerability specifically targets the memory management routines responsible for processing DjVu document structures, where insufficient bounds checking allows attackers to overwrite adjacent memory locations on the heap. The affected version range spans from 6.1.4 Build 27351 through the vulnerable builds prior to the security patch release, making a significant portion of the plugin's user base susceptible to exploitation.
The technical implementation of this vulnerability stems from improper input validation within the DjVu file parser's Sjbz chunk processing logic. When the browser plugin encounters a crafted djvu file containing malicious Sjbz chunks, the parsing routine fails to properly validate the chunk size or content boundaries before attempting to copy data into heap-allocated buffers. This allows an attacker to write beyond the allocated buffer limits, potentially overwriting critical memory structures including function pointers, return addresses, or other control data. The heap-based nature of the overflow means that the memory corruption occurs in the program's dynamic memory allocation space rather than on the stack, making exploitation more complex but still achievable through careful crafting of the malicious input. The vulnerability aligns with CWE-121 Heap-based Buffer Overflow, which specifically addresses buffer overflows occurring in heap memory regions where insufficient bounds checking permits writes beyond allocated buffer boundaries.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential system compromise and data breaches. Remote attackers can leverage this vulnerability to inject and execute arbitrary code within the context of the browser process, potentially leading to full system compromise if the browser has elevated privileges. The exploitation requires only a user to open a maliciously crafted djvu file, making it particularly dangerous in phishing scenarios or when users browse untrusted websites. The attack vector through the browser plugin interface means that successful exploitation can bypass traditional network security controls, as the attack occurs within the trusted browser environment. This vulnerability creates opportunities for attackers to establish persistent access, harvest sensitive information, or deploy additional malware components. The security implications are particularly severe given that DjVu files are commonly used for document sharing and can be embedded in web pages, increasing the attack surface and potential impact.
Mitigation strategies for CVE-2012-5006 primarily focus on immediate patch deployment and operational security enhancements. Organizations should prioritize updating the Caminova DjVu Browser Plug-in to version 6.1.4.27993 or later, which includes the necessary memory bounds checking and input validation fixes. Network administrators should consider implementing browser security policies that disable or restrict DjVu plugin functionality, particularly in environments where the risk of encountering malicious content is high. The implementation of web application firewalls and content filtering systems can help detect and block potentially malicious djvu files before they reach end users. Additionally, security monitoring should be enhanced to detect unusual memory access patterns or process behavior that might indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving execution through browser plugins and privilege escalation, requiring defensive measures that address both the initial compromise vector and potential post-exploitation activities. Regular security assessments and vulnerability scanning should include checks for outdated browser plugins and ensure that all components maintain current security patches to prevent similar vulnerabilities from being exploited in the future.