CVE-2016-6169 in Foxit Reader
Summary
by MITRE
Heap-based buffer overflow in Foxit Reader and PhantomPDF 7.3.4.311 and earlier on Windows allows remote attackers to cause a denial of service (memory corruption and application crash) or potentially execute arbitrary code via the Bezier data in a crafted PDF file.
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Analysis
by VulDB Data Team • 01/02/2020
The heap-based buffer overflow vulnerability identified as CVE-2016-6169 affects Foxit Reader and PhantomPDF versions 7.3.4.311 and earlier on Windows platforms. This critical security flaw resides in the PDF rendering engine's handling of Bezier curve data within maliciously crafted PDF files, representing a classic example of improper input validation that can lead to severe memory corruption issues. The vulnerability manifests when the application processes malformed Bezier data structures that exceed allocated buffer boundaries, creating conditions where attacker-controlled data can overwrite adjacent memory locations. This type of vulnerability falls under CWE-121 Heap-based Buffer Overflow, which specifically addresses buffer overflows occurring in heap memory allocations where insufficient bounds checking allows data to overflow into adjacent memory regions.
The technical exploitation of this vulnerability involves crafting a PDF file containing specially formatted Bezier curve data that triggers the buffer overflow during document rendering. When the vulnerable application attempts to process this malformed data, it allocates insufficient memory for the Bezier curve operations, allowing the attacker to write beyond the intended buffer boundaries. The memory corruption typically results in application crashes or can potentially be leveraged for arbitrary code execution if proper exploit mitigations are not in place. This vulnerability represents a significant threat to enterprise environments where PDF documents are frequently opened and processed, as the attack vector requires no special privileges and can be delivered through standard email attachments or web downloads.
The operational impact of CVE-2016-6169 extends beyond simple denial of service scenarios, as the potential for arbitrary code execution creates serious risks for information confidentiality and system integrity. Organizations utilizing affected versions of Foxit Reader and PhantomPDF face elevated risk of targeted attacks where adversaries could leverage this vulnerability to establish persistent access to systems, escalate privileges, or exfiltrate sensitive data. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to execute malicious code within the context of the vulnerable application. This makes the vulnerability particularly dangerous in environments where PDF processing is automated or where users frequently open untrusted documents from external sources.
Organizations should prioritize immediate remediation by upgrading to patched versions of Foxit Reader and PhantomPDF, as the vulnerability affects widely used PDF processing software across multiple industry sectors. The recommended mitigation strategy includes implementing strict document filtering policies that scan all incoming PDF files for suspicious content, deploying application whitelisting controls to prevent execution of untrusted PDF viewers, and enabling memory protection mechanisms such as DEP and ASLR. Security teams should also consider network-based intrusion detection systems that can identify and block malicious PDF content containing known exploit patterns, while maintaining regular vulnerability assessments to identify similar issues in other PDF rendering components throughout the enterprise infrastructure.