CVE-2019-20827 in Foxit
Summary
by MITRE
An issue was discovered in Foxit PhantomPDF Mac 3.3 and Foxit Reader for Mac before 3.3. It allows stack consumption because of interaction between ICC-Based color space and Alternate color space.
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Analysis
by VulDB Data Team • 10/22/2020
The vulnerability identified as CVE-2019-20827 represents a critical stack consumption issue affecting Foxit PhantomPDF Mac version 3.3 and Foxit Reader for Mac versions prior to 3.3. This flaw manifests through the interaction between ICC-Based color space and Alternate color space implementations within the PDF rendering engine. The vulnerability exploits a fundamental memory management weakness that occurs during the processing of PDF documents containing specific color space configurations, creating a potential avenue for denial of service attacks or unintended system behavior.
The technical root cause of this vulnerability lies in the improper handling of color space definitions within PDF documents, specifically when ICC-Based color spaces interact with Alternate color spaces. During the rendering process, the PDF parser fails to adequately validate or limit the stack memory consumption when processing these complex color space combinations. This results in excessive stack usage that can lead to stack overflow conditions or exhaustion of available stack memory resources. The flaw is classified under CWE-772, which deals with missing Release of Memory after Effective Lifetime, and more specifically aligns with CWE-121, Stack-based Buffer Overflow, due to the stack consumption characteristics observed in the affected applications.
From an operational perspective, this vulnerability presents significant risks to organizations relying on Foxit PDF readers for document processing and viewing. Attackers could potentially craft malicious PDF documents containing crafted ICC-Based and Alternate color space configurations to trigger the stack consumption behavior. The impact extends beyond simple denial of service, as successful exploitation could lead to application crashes, system instability, or in worst-case scenarios, potential privilege escalation if the applications run with elevated permissions. This vulnerability particularly affects environments where users frequently open untrusted PDF documents, making it a prime target for social engineering attacks.
The attack surface for this vulnerability is substantial given the widespread use of Foxit Reader and PhantomPDF across various industries including finance, healthcare, and government sectors. The exploitation requires minimal technical expertise, as it only requires crafting a specific PDF document structure rather than sophisticated attack vectors. This makes it particularly dangerous in enterprise environments where users may inadvertently open malicious documents through email attachments or web downloads. The vulnerability's impact is amplified by the fact that PDF documents are commonly used for sharing sensitive information, making this a potential vector for data exposure or system compromise.
Mitigation strategies for CVE-2019-20827 should prioritize immediate software updates to the latest versions of Foxit Reader and PhantomPDF that contain patches addressing the stack consumption issue. Organizations should implement strict document filtering policies, particularly for PDF files received from external sources or untrusted entities. Network-based security controls including PDF inspection appliances and web proxies should be configured to scan and block potentially malicious documents before they reach end-user systems. Additionally, security teams should consider implementing sandboxing mechanisms for PDF processing and regularly monitor for indicators of compromise related to this vulnerability. The remediation process should also include user education programs to raise awareness about the risks of opening untrusted PDF documents and the importance of keeping software updated. Organizations should conduct vulnerability assessments to identify systems running affected versions and establish monitoring procedures to detect potential exploitation attempts. This vulnerability serves as a reminder of the critical importance of proper memory management in PDF rendering engines and the need for robust input validation when processing complex document formats.