CVE-2010-1773 in Chrome
Summary
by MITRE
Off-by-one error in the toAlphabetic function in rendering/RenderListMarker.cpp in WebCore in WebKit before r59950, as used in Google Chrome before 5.0.375.70, allows remote attackers to obtain sensitive information, cause a denial of service (memory corruption and application crash), or possibly execute arbitrary code via vectors related to list markers for HTML lists, aka rdar problem 8009118.
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Analysis
by VulDB Data Team • 09/25/2021
The vulnerability identified as CVE-2010-1773 represents a critical off-by-one error within the WebKit rendering engine's implementation of HTML list marker handling. This flaw exists in the toAlphabetic function located in the rendering/RenderListMarker.cpp file of WebCore, which is the core rendering component that processes HTML elements for display in web browsers. The vulnerability was present in WebKit versions prior to revision r59950 and specifically affected Google Chrome versions before 5.0.375.70, making it a widespread issue across multiple browser versions and user bases.
The technical nature of this vulnerability stems from an improper boundary check in the toAlphabetic function that handles the conversion of numeric list markers to alphabetic characters. When processing HTML lists with specific marker configurations, the function fails to properly validate array indices, leading to memory access violations. This off-by-one error creates a condition where memory beyond the allocated buffer can be accessed or modified, potentially exposing sensitive information stored in adjacent memory locations. The flaw allows attackers to manipulate the list marker rendering process through carefully crafted HTML input that triggers the vulnerable code path.
The operational impact of this vulnerability extends across multiple security domains, creating opportunities for attackers to exploit the memory corruption for various malicious purposes. Remote attackers can leverage this vulnerability to cause application crashes and denial of service conditions, effectively disrupting user browsing sessions. More critically, the memory corruption aspect opens possibilities for arbitrary code execution, allowing attackers to potentially gain control over the affected browser process. The vulnerability's classification as a memory corruption issue aligns with CWE-121, which addresses heap-based buffer overflow conditions, and represents a classic example of how improper bounds checking can lead to severe security implications.
The attack surface for this vulnerability is particularly concerning given the ubiquity of HTML list elements in web content and the widespread use of affected browsers. Attackers can craft malicious web pages containing specially formatted HTML lists that, when rendered by the vulnerable browser, trigger the off-by-one error. This approach leverages the standard web browsing environment without requiring special privileges or complex exploitation techniques, making it particularly dangerous for end users. The vulnerability's connection to the rdar problem 8009118 indicates it was recognized and tracked by Apple's internal development systems, suggesting the issue was well-documented and understood within the browser development community.
Mitigation strategies for this vulnerability require immediate patching of affected browser versions, as the flaw exists in fundamental rendering logic that cannot be effectively addressed through configuration changes or user behavior modifications. Organizations should prioritize updating to Chrome 5.0.375.70 or later versions that contain the fix for this specific memory handling issue. The patch implementation addresses the boundary checking error in the toAlphabetic function, ensuring that array accesses remain within proper memory boundaries. Security teams should also consider implementing web content filtering measures that can detect and block suspicious HTML list marker patterns, though such measures represent defensive tactics rather than complete solutions to the underlying memory corruption issue. This vulnerability demonstrates the critical importance of thorough input validation and boundary checking in browser rendering engines, where even seemingly benign HTML elements can become attack vectors when implementation flaws exist in core functionality.