CVE-2012-1931 in Web Browser
Summary
by MITRE
Opera before 11.62 on UNIX, when used in conjunction with an unspecified printing application, allows local users to overwrite arbitrary files via a symlink attack on a temporary file during printing.
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Analysis
by VulDB Data Team • 03/22/2021
This vulnerability exists in Opera web browser versions prior to 11.62 on unix operating systems and represents a critical file system security flaw that enables local privilege escalation through improper temporary file handling during printing operations. The issue stems from the browser's failure to properly validate file paths when interacting with external printing applications, creating an exploitable race condition scenario that allows malicious users to substitute legitimate temporary files with symbolic links pointing to sensitive system locations. The vulnerability specifically manifests when Opera generates temporary files during the printing process and fails to implement proper security controls to prevent symbolic link attacks.
The technical implementation of this flaw involves the browser's printing subsystem creating temporary files in predictable locations without adequate permission checks or atomic file creation mechanisms. When Opera interacts with an external printing application, it may create temporary files that are subsequently processed by the printing system. An attacker with local access can exploit this by creating symbolic links in the same directory where Opera expects to find temporary files, effectively redirecting the printing process to overwrite arbitrary files on the system. This type of vulnerability is classified as a race condition attack where the timing between file creation and file access creates a window for exploitation. The flaw aligns with CWE-367 which specifically addresses Time-of-Check to Time-of-Use (TOCTOU) vulnerabilities, where the state of a resource changes between the time it is checked and when it is accessed.
The operational impact of this vulnerability extends beyond simple file overwrites as it can potentially enable attackers to modify critical system files, configuration data, or even execute malicious code with the privileges of the user running the browser. Since the vulnerability operates at the local user level without requiring network access or authentication, it presents a significant risk in multi-user environments where attackers can leverage this weakness to escalate privileges or compromise system integrity. The attack vector is particularly concerning because it leverages the legitimate printing functionality of the browser, making it harder to detect through traditional security monitoring. This vulnerability can be exploited to modify browser configuration files, system binaries, or other sensitive data, potentially leading to persistent access or complete system compromise.
The recommended mitigations for this vulnerability include immediate upgrading to Opera version 11.62 or later, which implements proper temporary file handling and security controls to prevent symbolic link attacks. System administrators should also implement proper file system permissions and access controls to limit the ability of local users to manipulate temporary file locations. Additional protective measures include disabling unnecessary printing functionality when not required, implementing proper monitoring for suspicious file system activities, and ensuring that the printing applications used are also properly secured against similar vulnerabilities. Organizations should also consider implementing the principle of least privilege, ensuring that browser processes run with minimal required permissions and that temporary file directories have appropriate access controls to prevent unauthorized symbolic link creation. This vulnerability demonstrates the importance of secure coding practices in handling temporary files and the necessity of implementing proper input validation and file system security controls in all applications that interact with external system components.