CVE-2017-6841 in PoDoFo
Summary
by MITRE
The GraphicsStack::TGraphicsStackElement::~TGraphicsStackElement function in graphicsstack.h in PoDoFo 0.9.5 allows remote attackers to cause a denial of service (NULL pointer dereference) via a crafted file.
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Analysis
by VulDB Data Team • 10/09/2024
The vulnerability identified as CVE-2017-6841 resides within the PoDoFo library version 0.9.5, specifically within the GraphicsStack::TGraphicsStackElement::~TGraphicsStackElement destructor function located in graphicsstack.h. This flaw represents a classic null pointer dereference vulnerability that can be exploited remotely through the careful crafting of malicious PDF files. The issue manifests when the destructor attempts to access a null pointer during the cleanup process of graphics stack elements, leading to an application crash and subsequent denial of service condition.
The technical implementation of this vulnerability stems from inadequate null pointer validation within the destructor logic of the graphics stack element class. When processing malformed PDF content, the graphics stack management system fails to properly validate pointer states before attempting memory cleanup operations. This particular weakness falls under the CWE-476 category of NULL Pointer Dereference, which is a fundamental programming error where software attempts to access memory through a null pointer reference. The vulnerability operates at the application layer and can be classified as a remote code execution risk, though in this specific case it manifests as a denial of service rather than arbitrary code execution.
From an operational perspective, this vulnerability creates significant risks for any system or application that relies on PoDoFo for PDF processing, particularly in server environments or applications handling untrusted PDF files from external sources. Attackers can craft specially designed PDF documents that, when processed by vulnerable applications, trigger the null pointer dereference during the destruction phase of graphics stack elements. This results in immediate application termination and prevents legitimate users from accessing the affected service, effectively creating a denial of service condition that can be exploited at scale.
The exploitation of CVE-2017-6841 aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to privilege escalation and denial of service operations. The vulnerability demonstrates how seemingly minor memory management flaws can be leveraged to disrupt service availability, which is a core component of the denial of service tactic category. Organizations utilizing PoDoFo for PDF processing should consider this vulnerability as part of their broader security posture assessment, especially in environments where PDF processing is automated or occurs without proper input sanitization.
Mitigation strategies for this vulnerability primarily focus on immediate software updates and patches provided by the PoDoFo development team. System administrators should prioritize upgrading to PoDoFo versions that contain fixed implementations of the graphics stack element destructor. Additionally, implementing proper input validation and sanitization measures when processing PDF files can serve as an effective compensating control. Organizations should also consider deploying network-based intrusion detection systems that can identify and block suspicious PDF content patterns that may trigger this vulnerability. The remediation process should include thorough testing of patched versions to ensure that the fix does not introduce regressions in legitimate PDF processing functionality.