CVE-2007-0644 in Safari
Summary
by MITRE
Format string vulnerability in Apple Safari 2.0.4 (419.3) allows remote user-assisted attackers to cause a denial of service (crash) via format string specifiers in filenames that are not properly handled when calling the (1) NSLog and (2) NSBeginAlertSheet Apple AppKit functions.
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Analysis
by VulDB Data Team • 03/13/2025
This vulnerability resides in Apple Safari 2.0.4 version 419.3 and represents a classic format string vulnerability within the application's handling of user-provided input. The flaw specifically affects the AppKit framework functions NSLog and NSBeginAlertSheet which are responsible for logging and displaying alert dialogs respectively. When Safari processes filenames containing improperly handled format string specifiers, the application fails to properly sanitize these inputs before passing them to the vulnerable functions, creating a condition where maliciously crafted filenames can trigger unexpected behavior.
The technical execution of this vulnerability occurs when a remote attacker constructs a filename containing format string specifiers such as %s, %d, or other printf-style formatting characters and presents this filename to Safari. When Safari attempts to display or log this filename through the NSLog or NSBeginAlertSheet functions, the application's failure to properly handle the format specifiers causes memory corruption or unexpected program execution paths. This leads to application instability and ultimately results in a denial of service condition where Safari crashes and becomes unavailable to the user.
From an operational impact perspective, this vulnerability creates a remote user-assisted attack vector that requires minimal privileges to exploit. The attacker need only convince a victim to interact with a specially crafted web page or file that contains the malicious filename, making this a particularly dangerous vulnerability in social engineering scenarios. The vulnerability affects the core functionality of Safari's user interface, as both NSLog and NSBeginAlertSheet are fundamental components used throughout the application for displaying information and handling user interactions. This means that the crash can occur at various points during normal browsing operations, potentially disrupting user sessions and rendering the browser unusable.
The vulnerability demonstrates characteristics consistent with CWE-134, which specifically addresses format string vulnerabilities where format strings are constructed from user-controlled data without proper sanitization. This weakness falls under the broader category of software security flaws that can lead to arbitrary code execution or denial of service conditions. The ATT&CK framework would categorize this vulnerability under T1203, which covers Obfuscated Files or Information, as attackers might need to craft filenames that appear benign while containing malicious format specifiers. The impact extends beyond simple denial of service as it represents a fundamental flaw in input validation and string handling within the application's core libraries.
Mitigation strategies should focus on input validation and proper string handling practices. Apple should implement comprehensive sanitization of all user-provided filenames before passing them to logging or alert functions, ensuring that format specifiers are properly escaped or removed. The fix should involve updating the AppKit framework to properly handle format strings through functions like vsnprintf or similar safe string operations that prevent format string exploitation. Additionally, implementing proper bounds checking and input validation at the application level would prevent malformed data from reaching vulnerable functions. Users should be advised to keep their Safari installations updated to versions that address this vulnerability, as the patch would typically involve code modifications to the core logging and alert handling mechanisms within the application's framework components.