CVE-2020-12247 in Foxit
Summary
by MITRE
In Foxit Reader and PhantomPDF before 10.0.1, and PhantomPDF before 9.7.3, attackers can obtain sensitive information from an out-of-bounds read because a text-string index continues to be used after splitting a string into two parts. A crash may also occur.
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Analysis
by VulDB Data Team • 09/04/2020
The vulnerability identified as CVE-2020-12247 represents a critical out-of-bounds read flaw affecting Foxit Reader and PhantomPDF software versions prior to 10.0.1 and 9.7.3 respectively. This vulnerability stems from improper handling of text string manipulation within the PDF processing engine, specifically when splitting text strings into multiple components. The flaw occurs during the parsing of PDF documents where the application fails to properly validate index boundaries after string splitting operations, creating a scenario where subsequent memory accesses reference invalid memory locations. This type of vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions that can lead to information disclosure and system instability. The vulnerability is particularly concerning as it exists within the core PDF rendering functionality that processes documents containing text elements, making it exploitable through malicious PDF files crafted to trigger the specific code path.
The technical implementation of this vulnerability involves the application's text processing subsystem where it splits text strings during PDF parsing operations. When the system encounters a text string that requires splitting, it calculates an index position to determine where the split should occur. However, the application continues to reference this original index position even after the string has been modified or split, leading to memory access violations. This flaw can manifest in two primary ways: information disclosure through memory leaks that expose sensitive data from adjacent memory locations, and system crashes due to invalid memory access patterns. The out-of-bounds read occurs in the context of PDF text rendering where the application attempts to access character data beyond the bounds of the allocated string buffer, potentially revealing contents of other variables, stack data, or even system memory regions. This behavior aligns with ATT&CK technique T1059.007 for execution through PDF files and represents a classic example of a buffer over-read vulnerability that can be leveraged for both information gathering and denial-of-service attacks.
The operational impact of CVE-2020-12247 extends beyond simple crash conditions to encompass potential data leakage and system compromise. Attackers can exploit this vulnerability by crafting malicious PDF documents that trigger the specific text string splitting scenario, potentially gaining access to sensitive information stored in memory adjacent to the affected buffers. This information disclosure capability poses significant risks to organizations that process untrusted PDF documents, as the leaked data could include user credentials, system configuration details, or proprietary information. The vulnerability's exploitation requires minimal privileges and can be delivered through standard email attachments or web-based PDF viewers, making it particularly dangerous in enterprise environments where PDF processing is common. The crash potential further compounds the risk by enabling denial-of-service attacks that can disrupt legitimate business operations. Organizations using affected versions of Foxit Reader or PhantomPDF face increased exposure to targeted attacks, especially in environments where PDF documents are frequently exchanged or automatically processed without proper security scanning.
Mitigation strategies for CVE-2020-12247 primarily involve immediate software updates to the patched versions of Foxit Reader and PhantomPDF, specifically versions 10.0.1 and 9.7.3 respectively. Organizations should prioritize deployment of these patches across all systems where the vulnerable software is installed, particularly in environments processing external PDF documents. Additionally, implementing PDF security measures such as sandboxing, content filtering, and restricted file type handling can provide defense-in-depth protection. Network-based security controls including web application firewalls and email security gateways should be configured to scan and block potentially malicious PDF attachments. Regular vulnerability assessments and penetration testing should be conducted to identify any remaining instances of the vulnerable software within the organization's infrastructure. System administrators should also consider implementing automated patch management solutions to ensure timely deployment of security updates. The vulnerability's nature as a memory corruption issue also warrants enhanced system monitoring and intrusion detection capabilities to identify potential exploitation attempts. Organizations should maintain detailed inventory records of all software installations to quickly identify and remediate any remaining vulnerable systems that may have been overlooked during initial patching efforts.