CVE-2003-0077 in hanterm-xf
Summary
by MITRE
The hanterm (hanterm-xf) terminal emulator 2.0.5 and earlier, and possibly later versions, allows attackers to modify the window title via a certain character escape sequence and then insert it back to the command line in the user s terminal, e.g. when the user views a file containing the malicious sequence, which could allow the attacker to execute arbitrary commands.
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Analysis
by VulDB Data Team • 05/29/2019
The vulnerability identified as CVE-2003-0077 represents a critical security flaw in the hanterm terminal emulator version 2.0.5 and earlier, with potential impacts extending to later versions. This vulnerability falls under the category of terminal emulation security issues that can lead to command injection attacks through carefully crafted escape sequences. The hanterm-xf terminal emulator, commonly used in Korean language environments, processes terminal escape sequences in a manner that fails to properly sanitize user input, creating a dangerous attack vector for malicious actors.
The technical flaw resides in how the terminal emulator handles specific character escape sequences that can be embedded within terminal output. When an attacker crafts a malicious escape sequence designed to modify the window title, this sequence can then be embedded within file contents or other terminal output. The vulnerability specifically exploits the terminal emulator's failure to properly validate and sanitize escape sequences during processing, allowing attackers to insert sequences that manipulate the terminal window title. This seemingly innocuous manipulation becomes dangerous when the malicious sequence is later displayed to users, as it can be inadvertently executed when users interact with files containing these sequences.
The operational impact of this vulnerability extends beyond simple window title manipulation to potentially enable full command execution. When users view files containing the malicious escape sequences, the terminal emulator processes these sequences and inserts them back into the command line context. This creates an environment where attackers can craft escape sequences that, when executed in the terminal context, can trigger arbitrary command execution. The vulnerability essentially allows attackers to inject malicious commands into the terminal session through seemingly benign file viewing operations, making it particularly dangerous in environments where users frequently view files from untrusted sources.
This vulnerability aligns with CWE-15 (External Control of System or Configuration Setting) and CWE-74 (Improper Neutralization of Special Elements in Output) within the Common Weakness Enumeration framework, demonstrating how improper handling of terminal escape sequences can lead to command injection attacks. The attack pattern corresponds to techniques described in the MITRE ATT&CK framework under T1059 (Command and Scripting Interpreter) and T1068 (Exploitation for Privilege Escalation), where attackers leverage terminal emulation flaws to execute arbitrary code. The vulnerability essentially creates a path for attackers to escalate privileges and execute malicious commands through terminal manipulation.
The recommended mitigations include immediate upgrading to hanterm versions that properly sanitize escape sequences and validate terminal input. System administrators should implement strict input validation for all terminal escape sequences and consider implementing terminal emulation restrictions that prevent certain dangerous escape sequences from being processed. Additionally, users should be educated about the risks of viewing files from untrusted sources, and organizations should consider implementing terminal security policies that limit the execution of potentially malicious escape sequences. The most effective long-term solution involves ensuring that all terminal emulators properly implement input sanitization and escape sequence validation to prevent the injection of malicious commands through terminal manipulation.