CVE-2010-1401 in Safari
Summary
by MITRE
Use-after-free vulnerability in the Cascading Style Sheets (CSS) implementation in WebKit in Apple Safari before 5.0 on Mac OS X 10.5 through 10.6 and Windows, and before 4.1 on Mac OS X 10.4, allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via vectors involving the :first-letter pseudo-element.
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Analysis
by VulDB Data Team • 09/15/2021
The CVE-2010-1401 vulnerability represents a critical use-after-free flaw within WebKit's CSS implementation that affected multiple Apple Safari versions across different operating systems. This vulnerability specifically targets the handling of the :first-letter pseudo-element in cascading style sheets, creating a dangerous condition where memory previously freed by the application is accessed again. The flaw exists in the browser's rendering engine that processes CSS rules and applies them to web page elements, making it particularly dangerous as it can be triggered through standard web browsing activities.
The technical nature of this vulnerability stems from improper memory management within WebKit's CSS parser and renderer. When processing CSS rules containing the :first-letter pseudo-element, the application fails to properly manage the memory allocation and deallocation cycle for objects representing text formatting properties. This creates a scenario where an attacker can manipulate CSS content to cause the browser to free memory associated with a CSS object and then subsequently access that same memory location, leading to undefined behavior. The use-after-free condition allows for potential code execution or system instability as the application attempts to operate on memory that has already been released back to the system heap.
The operational impact of CVE-2010-1401 extends beyond simple application crashes to potentially enable remote code execution on vulnerable systems. Attackers can craft malicious web pages containing specially formatted CSS that triggers the memory corruption when Safari processes the :first-letter pseudo-element. This vulnerability affects a broad range of systems including Mac OS X 10.5 through 10.6, Windows platforms, and older Mac OS X 10.4 systems, making it particularly dangerous as it spans multiple operating environments. The exploitability of this vulnerability means that users could be compromised simply by visiting a malicious website, without requiring any special user interaction beyond normal browsing behavior.
This vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software implementations, and demonstrates how improper memory management can create severe security risks. The attack pattern follows typical remote code execution vectors described in the MITRE ATT&CK framework under the technique of "Exploitation for Code Execution" where adversaries leverage memory corruption vulnerabilities to gain arbitrary code execution capabilities. Organizations affected by this vulnerability should prioritize immediate patching of Safari installations, as the window of exploitation remains significant due to the widespread use of affected Safari versions. System administrators should also implement network-based protections including web content filtering and browser security policies to reduce the risk of exploitation while patches are deployed across affected systems.