CVE-2014-3121 in rxvt-unicode
Summary
by MITRE
rxvt-unicode before 9.20 does not properly handle OSC escape sequences, which allows user-assisted remote attackers to manipulate arbitrary X window properties and execute arbitrary commands.
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Analysis
by VulDB Data Team • 12/17/2024
The vulnerability identified as CVE-2014-3121 affects rxvt-unicode terminal emulators prior to version 9.20, presenting a critical security risk through improper handling of Operating System Command (OSC) escape sequences. This flaw exists within the terminal's interpretation of control sequences that are typically used for communication between applications and the terminal emulator, creating a pathway for malicious actors to exploit the system through seemingly benign user interactions. The vulnerability falls under the category of improper input validation and control sequence handling, which can be categorized under CWE-20, indicating improper input validation within the software's parsing logic.
The technical implementation of this vulnerability stems from the terminal emulator's failure to properly sanitize or validate OSC escape sequences that are processed during runtime. When a user interacts with a malicious application or webpage that sends specially crafted escape sequences, the terminal emulator interprets these sequences as commands that manipulate the underlying X window properties. This allows attackers to execute arbitrary code with the privileges of the user running the terminal emulator, effectively bypassing normal security boundaries that should protect the system from unauthorized command execution. The vulnerability specifically leverages the X11 windowing system's property manipulation capabilities through the terminal's improper handling of escape sequences.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can enable attackers to gain full control over the affected system. Since rxvt-unicode is commonly used in Unix-like environments including Linux distributions and BSD systems, the attack surface is broad across various operating systems. An attacker could potentially execute malicious commands, access sensitive data, modify system configurations, or establish persistent access through this vulnerability. The user-assisted nature of the attack means that the target must interact with a malicious application or webpage, but once triggered, the consequences can be severe. This vulnerability directly maps to ATT&CK technique T1059.007 for Command and Scripting Interpreter, as it enables execution of arbitrary commands through terminal manipulation.
The exploitation of CVE-2014-3121 typically requires social engineering to convince users to interact with malicious content, but once successful, the attack can be devastating. The vulnerability demonstrates how seemingly innocuous terminal features can become attack vectors when proper input validation is not implemented. System administrators and security professionals should consider this vulnerability as part of their broader security posture assessment, particularly in environments where users may encounter untrusted web content or applications. The fix for this vulnerability requires updating to rxvt-unicode version 9.20 or later, which includes proper sanitization of OSC escape sequences. Organizations should also implement network segmentation and user education to reduce the risk of successful exploitation through social engineering tactics that could lead users to interact with malicious content.