CVE-2015-8981 in PoDoFo
Summary
by MITRE
Heap-based buffer overflow in the PdfParser::ReadXRefSubsection function in base/PdfParser.cpp in PoDoFo allows attackers to have unspecified impact via vectors related to m_offsets.size.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/24/2024
The vulnerability identified as CVE-2015-8981 represents a critical heap-based buffer overflow within the PoDoFo PDF processing library, specifically within the PdfParser::ReadXrefSubsection function located in base/PdfParser.cpp. This flaw arises from inadequate input validation when processing PDF cross-reference subsections, creating a scenario where attacker-controlled data can corrupt heap memory. The vulnerability manifests when the m_offsets.size variable is manipulated through crafted PDF input, leading to potential memory corruption that can be exploited for arbitrary code execution or denial of service conditions. The heap-based nature of this overflow means that the attacker can overwrite adjacent memory regions, potentially compromising the application's stability and security. This vulnerability directly relates to CWE-121, heap-based buffer overflow, which is classified as a critical weakness in software security. The attack surface is particularly concerning as PDF processing libraries are widely used across various applications and platforms, making this vulnerability exploitable in numerous contexts.
The technical implementation of this vulnerability involves the PdfParser::ReadXrefSubsection function failing to properly validate the size of the m_offsets array before performing memory operations. When processing malformed PDF files containing crafted cross-reference subsections, the parser does not adequately check boundary conditions for the offsets array, allowing an attacker to manipulate the m_offsets.size value to exceed allocated memory boundaries. This results in memory corruption that can be leveraged to execute arbitrary code within the context of the application using PoDoFo. The vulnerability is particularly dangerous because PDF processing occurs in memory-constrained environments, and the heap corruption can lead to unpredictable behavior including application crashes, data corruption, or complete system compromise. The attacker can craft malicious PDF documents that, when processed by vulnerable applications, trigger the buffer overflow condition through careful manipulation of the cross-reference table structure.
The operational impact of CVE-2015-8981 extends beyond simple denial of service to encompass potential full system compromise, depending on the target application's execution environment and privileges. Applications that utilize PoDoFo for PDF processing, including web browsers, document management systems, and security tools, become vulnerable to exploitation when they process untrusted PDF content. The vulnerability's exploitation can result in privilege escalation, data exfiltration, or persistent backdoor installation, particularly when the target application runs with elevated privileges. Security researchers have identified this vulnerability as particularly dangerous in web-based environments where PDF processing occurs in sandboxed contexts, as the heap corruption can potentially bypass memory protection mechanisms like DEP and ASLR. The vulnerability also aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation may involve injecting malicious code into memory regions that are subsequently executed.
Mitigation strategies for CVE-2015-8981 should focus on immediate patching of affected PoDoFo versions, implementation of input validation controls, and deployment of security monitoring solutions. Organizations should prioritize updating to PoDoFo versions that contain the patched PdfParser::ReadXrefSubsection function, which properly validates the m_offsets.size variable and implements appropriate bounds checking. Additionally, implementing defensive programming practices such as using safe string manipulation functions, enabling compiler security features like stack canaries, and deploying memory protection mechanisms can help reduce exploitation success rates. Network-based detection measures should monitor for suspicious PDF file patterns and malformed cross-reference structures that may indicate exploitation attempts. The vulnerability also highlights the importance of regular security assessments and penetration testing of PDF processing components, as similar issues may exist in other PDF libraries and processing frameworks. Organizations should also consider implementing sandboxing mechanisms for PDF processing to contain potential exploitation attempts and limit the impact of successful attacks on system resources and data integrity.