CVE-2010-1797 in Foxit
Summary
by MITRE
Multiple stack-based buffer overflows in the cff_decoder_parse_charstrings function in the CFF Type2 CharStrings interpreter in cff/cffgload.c in FreeType before 2.4.2, as used in Apple iOS before 4.0.2 on the iPhone and iPod touch and before 3.2.2 on the iPad, allow remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via crafted CFF opcodes in embedded fonts in a PDF document, as demonstrated by JailbreakMe. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 09/27/2024
The vulnerability identified as CVE-2010-1797 represents a critical stack-based buffer overflow in the FreeType font rendering library that affects multiple Apple iOS devices. This flaw exists within the cff_decoder_parse_charstrings function located in the cff/cffgload.c file, which serves as the CFF Type2 CharStrings interpreter responsible for processing font data in PostScript Compact Font Format. The vulnerability specifically manifests when processing crafted CFF opcodes embedded within PDF documents, creating a remote code execution vector that has been exploited in real-world scenarios including the JailbreakMe attack vector. The affected versions include Apple iOS before 4.0.2 for iPhone and iPod touch, and before 3.2.2 for iPad, demonstrating the widespread impact across Apple's mobile platform ecosystem. This vulnerability operates at the intersection of font processing and memory corruption, leveraging the complex nature of PostScript font interpretation to achieve unauthorized code execution.
The technical implementation of this vulnerability stems from inadequate input validation within the CFF Type2 CharStrings interpreter where the cff_decoder_parse_charstrings function fails to properly bounds-check data structures during font parsing operations. When the parser encounters specially crafted CFF opcodes embedded within font data contained in PDF documents, it proceeds to write data beyond the allocated stack buffer boundaries, resulting in memory corruption that can be leveraged by attackers to execute arbitrary code. This flaw corresponds to CWE-121 Stack-based Buffer Overflow, which is classified under the broader category of memory safety issues in software development. The attack vector is particularly dangerous because it operates through legitimate PDF document processing, making it difficult to detect and prevent through traditional network security measures. The vulnerability's exploitation requires minimal user interaction since it can be triggered simply by opening a malicious PDF document containing the crafted font data.
The operational impact of CVE-2010-1797 extends beyond simple denial of service to encompass full remote code execution capabilities that can compromise entire mobile devices. Attackers can leverage this vulnerability to bypass device security mechanisms and gain unauthorized access to system resources, potentially enabling further exploitation or data exfiltration. The memory corruption resulting from the buffer overflow creates unpredictable behavior that can be manipulated to redirect program execution flow, allowing attackers to inject and execute malicious code within the context of the affected applications. This vulnerability particularly affects Apple's mobile ecosystem because the FreeType library is deeply integrated into iOS font rendering processes, making it a critical component in the attack chain. The flaw's presence in iOS versions prior to 4.0.2 and 3.2.2 respectively demonstrates how font processing vulnerabilities can create persistent security risks across operating system versions.
Mitigation strategies for CVE-2010-1797 focus on both immediate patching and operational security measures to protect against exploitation. The primary remediation involves upgrading to FreeType version 2.4.2 or later, which includes proper bounds checking and input validation within the cff_decoder_parse_charstrings function to prevent buffer overflow conditions. Apple addressed this vulnerability through iOS security updates that included patches to the FreeType library and enhanced PDF processing validation. Organizations should implement additional protective measures such as PDF document filtering to prevent execution of potentially malicious embedded fonts, network-based intrusion detection systems to monitor for exploitation attempts, and regular security assessments of font processing components. The vulnerability's classification under ATT&CK technique T1059.007 for process injection and T1068 for exploit for privilege escalation highlights the need for comprehensive security monitoring and incident response procedures. Security teams should also consider implementing application whitelisting policies to restrict font processing to trusted sources and maintain updated threat intelligence feeds to detect similar vulnerabilities in font rendering libraries.