CVE-2009-1705 in Safari
Summary
by MITRE
CoreGraphics in Apple Safari before 4.0 on Windows does not properly use arithmetic during automatic hinting of TrueType fonts, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via crafted font data.
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Analysis
by VulDB Data Team • 07/31/2019
The vulnerability identified as CVE-2009-1705 represents a critical memory corruption flaw within Apple Safari's CoreGraphics rendering engine on Windows platforms. This issue specifically affects Safari versions prior to 4.0 and stems from improper arithmetic handling during the automatic hinting process of TrueType font files. The flaw manifests when the browser processes specially crafted font data that exploits mathematical operations within the font rendering pipeline, creating conditions that can lead to unpredictable memory state modifications.
The technical exploitation of this vulnerability occurs through the manipulation of TrueType font files that contain malicious arithmetic sequences during the hinting phase. CoreGraphics, which is responsible for font rendering and text display in Safari, performs automatic hinting to optimize font appearance on screen displays. When processing malformed font data, the arithmetic calculations used in this hinting process fail to properly validate input parameters, leading to buffer overflows or memory corruption patterns. This memory corruption directly impacts the application's heap management and can be leveraged to overwrite critical memory locations, potentially allowing remote attackers to execute arbitrary code with the privileges of the affected browser process.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass full remote code execution capabilities. Attackers can craft malicious font files that, when rendered by Safari, trigger memory corruption that can be exploited to gain control over the browser's execution context. The vulnerability affects Windows users specifically, as the CoreGraphics implementation on Windows platforms contains the flawed arithmetic handling logic that differs from the macOS counterparts. This creates a unique attack surface where web-based font rendering becomes a vector for sophisticated exploitation techniques that can compromise user systems.
The security implications of this vulnerability align with CWE-129, which addresses improper validation of length parameters in memory operations, and CWE-125, which covers out-of-bounds read conditions. The attack pattern follows typical exploit development methodologies where font files serve as the delivery mechanism for memory corruption exploits. From an ATT&CK framework perspective, this vulnerability maps to T1203 (Exploitation for Client Execution) and T1059 (Command and Scripting Interpreter) as it enables attackers to execute code on victim machines through browser-based attacks. The vulnerability's exploitation requires minimal user interaction, as simply visiting a malicious website that serves the crafted font file can trigger the exploit, making it particularly dangerous for widespread deployment.
Mitigation strategies for CVE-2009-1705 primarily focus on immediate software updates and browser security enhancements. Users should upgrade to Safari 4.0 or later versions where the CoreGraphics font handling has been patched to properly validate arithmetic operations during hinting. Organizations should implement web content filtering to block suspicious font file downloads and consider disabling font rendering for untrusted content sources. Additionally, security configurations should include monitoring for unusual memory access patterns and implementing application sandboxing to limit the potential impact of successful exploitation attempts. The vulnerability highlights the importance of proper input validation in graphics rendering systems and demonstrates how seemingly benign font processing operations can become critical security attack vectors when mathematical operations are not properly safeguarded against malicious inputs.