CVE-2007-3944 in WebKit
Summary
by MITRE
Multiple heap-based buffer overflows in the Perl Compatible Regular Expressions (PCRE) library in the JavaScript engine in WebKit in Apple Safari 3 Beta before Update 3.0.3, and iPhone before 1.0.1, allow remote attackers to execute arbitrary code via certain JavaScript regular expressions. NOTE: this issue was originally reported only for MobileSafari on the iPhone. NOTE: it is not clear whether this stems from an issue in the original distribution of PCRE, which might already have a separate CVE identifier.
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Analysis
by VulDB Data Team • 07/23/2019
The vulnerability identified as CVE-2007-3944 represents a critical heap-based buffer overflow in the Perl Compatible Regular Expressions library implementation within WebKit's JavaScript engine. This flaw specifically affected Apple Safari 3 Beta versions prior to Update 3.0.3 and iPhone operating systems before version 1.0.1, creating a significant security risk that could be exploited by remote attackers to execute arbitrary code on vulnerable systems. The vulnerability stems from improper handling of regular expressions within the JavaScript engine, where maliciously crafted regex patterns could trigger memory corruption issues that bypass normal execution boundaries.
The technical implementation of this vulnerability involves the exploitation of memory management flaws within the PCRE library integration in WebKit's JavaScript engine. When processing certain JavaScript regular expressions, the engine fails to properly validate input length and buffer boundaries, leading to heap corruption that can be leveraged by attackers to overwrite adjacent memory locations. This type of vulnerability maps directly to CWE-121 Heap-based Buffer Overflow, which occurs when a program writes data past the end of a heap-allocated buffer, potentially allowing attackers to control program execution flow through memory corruption. The attack vector specifically targets the JavaScript engine's regex processing capabilities, where the buffer overflow occurs during the parsing and execution of malicious regular expressions.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a means to compromise user systems remotely without requiring any local privileges or user interaction beyond visiting a malicious webpage. This makes it particularly dangerous in the context of web-based attacks where users can be targeted through compromised websites or phishing campaigns. The vulnerability affects a wide range of Apple devices including desktop computers running Safari and mobile devices running MobileSafari, creating a substantial attack surface that could be exploited by threat actors targeting Apple ecosystem users. The fact that this vulnerability was initially reported specifically for MobileSafari indicates the severity of the issue in mobile environments where users may have less control over their security configurations.
Security mitigations for this vulnerability required immediate patching of affected Safari versions and iPhone operating systems through official updates from Apple. The fix involved correcting the buffer boundary checking mechanisms within the PCRE library implementation and strengthening input validation for regular expressions processed by the JavaScript engine. Organizations and users needed to apply these patches promptly to prevent exploitation, as the vulnerability could be exploited through web-based attacks without user interaction. The remediation efforts also highlighted the importance of proper input validation and memory safety practices in web browser implementations, particularly in JavaScript engines that handle complex regular expression processing. This vulnerability demonstrated the critical importance of regular security updates and the potential for seemingly benign features like regular expression processing to become attack vectors when not properly secured against malicious input.
The broader implications of this vulnerability extend to the security practices of web browser vendors and the importance of thorough security testing for core components like regular expression engines. This issue serves as a reminder of how deeply integrated components within browser architectures can become attack surfaces when proper security boundaries are not maintained. The vulnerability's classification as heap-based buffer overflow aligns with ATT&CK technique T1059.007 for Scripting, specifically targeting JavaScript execution environments where the attack chain could lead to full system compromise through code execution. The incident underscored the need for comprehensive security testing of all components within browser engines and the importance of maintaining updated security practices for third-party libraries like PCRE that are integrated into core browser functionality.