CVE-2017-6844 in PoDoFo
Summary
by MITRE
Buffer overflow in the PoDoFo::PdfParser::ReadXRefSubsection function in PdfParser.cpp in PoDoFo 0.9.4 allows remote attackers to have unspecified impact via a crafted file.
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Analysis
by VulDB Data Team • 09/09/2020
The vulnerability identified as CVE-2017-6844 represents a critical buffer overflow flaw within the PoDoFo library version 0.9.4, specifically within the PdfParser.cpp source file. This issue manifests in the PoDoFo::PdfParser::ReadXrefSubsection function where improper input validation and memory handling creates an exploitable condition that can be triggered through maliciously crafted pdf files. The vulnerability falls under the CWE-121 category of stack-based buffer overflow, which is a well-documented weakness in software security practices where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The PoDoFo library, widely used for pdf manipulation and generation across various applications, becomes a potential attack vector when processing untrusted pdf content.
The technical implementation of this vulnerability occurs during the parsing of pdf cross-reference subsections where the application fails to properly validate the size of data being read from the pdf file before attempting to store it in a fixed-size buffer. When an attacker crafts a pdf file containing malformed cross-reference data that exceeds the expected buffer boundaries, the application's memory management fails to prevent this overflow condition. The impact of such a vulnerability extends beyond simple application crashes as it can potentially enable arbitrary code execution, privilege escalation, or information disclosure depending on the execution environment and memory layout. The unspecified impact mentioned in the CVE description reflects the potential severity that can vary based on system configurations, memory protection mechanisms, and the specific attack vectors employed by threat actors.
From an operational perspective, this vulnerability poses significant risks to organizations that rely on PoDoFo for pdf processing within their applications, web services, or document management systems. The remote exploitation capability means that attackers can trigger this vulnerability through web-based pdf uploads, email attachments, or any other mechanism that allows untrusted pdf content to be processed by affected applications. The attack surface expands when considering that PoDoFo is integrated into numerous third-party applications, making the exploitation potential widespread. Security professionals should note that this vulnerability aligns with ATT&CK technique T1203 (Exploitation for Client Execution) and can be categorized under T1068 (Exploitation for Privilege Escalation) when successful exploitation occurs. Organizations using PoDoFo in production environments must consider this vulnerability as a critical threat that could lead to complete system compromise if exploited properly.
Mitigation strategies for CVE-2017-6844 should prioritize immediate patching of affected PoDoFo installations to version 0.9.5 or later where the buffer overflow has been addressed through proper input validation and memory bounds checking. Additionally, implementing input sanitization measures at the application level can provide defense-in-depth protection, including validating pdf file sizes, implementing strict parsing limits, and employing sandboxing techniques when processing untrusted pdf content. Network-based controls such as pdf file scanning, content filtering, and web application firewalls can help prevent malicious pdf files from reaching vulnerable applications. Organizations should also conduct thorough vulnerability assessments to identify all applications using affected PoDoFo versions and establish monitoring procedures to detect potential exploitation attempts. The remediation process should include updating all integrated systems, performing security testing to verify the patch effectiveness, and implementing proper security monitoring to detect any exploitation attempts against the patched systems.