CVE-2013-7416 in Curses
Summary
by MITRE
canto_curses/guibase.py in Canto Curses before 0.9.0 allows remote feed servers to execute arbitrary commands via shell metacharacters in a URL in a feed.
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Analysis
by VulDB Data Team • 04/07/2022
The vulnerability identified as CVE-2013-7416 resides within the canto_curses feed reader application, specifically in the guibase.py module that handles feed processing. This issue affects versions prior to 0.9.0 and represents a critical command injection flaw that enables remote attackers to execute arbitrary system commands through manipulated feed content. The vulnerability manifests when the application processes feed URLs containing shell metacharacters, creating a dangerous attack vector where malicious feed servers can compromise systems running vulnerable versions of Canto Curses.
The technical flaw stems from inadequate input validation and sanitization within the feed processing pipeline. When Canto Curses encounters a feed URL, it fails to properly escape or filter shell metacharacters such as semicolons, ampersands, backticks, or other command execution operators that could be present in the URL. This improper handling allows attackers to inject malicious commands that get executed within the shell context of the feed processing routine. The vulnerability aligns with CWE-78, which specifically addresses improper neutralization of special elements used in OS commands, making it a classic command injection vulnerability that can be exploited for arbitrary code execution.
The operational impact of this vulnerability extends beyond simple command execution to encompass complete system compromise. An attacker controlling a malicious feed server can execute commands with the privileges of the user running Canto Curses, potentially leading to privilege escalation, data exfiltration, or persistent backdoor installation. Given that feed readers often run continuously and may be used in automated environments, this vulnerability can provide attackers with sustained access to compromised systems. The remote nature of the attack means that victims need not interact with malicious content directly, as simply processing a compromised feed can trigger the exploitation.
Mitigation strategies for CVE-2013-7416 should prioritize immediate patching to version 0.9.0 or later, which contains the necessary input validation fixes. Organizations should also implement network-level controls such as feed filtering and URL validation at the perimeter to prevent access to known malicious feeds. The principle of least privilege should be enforced by running Canto Curses with minimal necessary permissions, ideally in restricted environments without access to sensitive system resources. Additionally, implementing proper input sanitization techniques including shell escaping, parameterized queries, and regular expression validation can help prevent similar vulnerabilities in other applications. This vulnerability demonstrates the importance of secure coding practices and input validation, particularly for applications that process external data from untrusted sources, aligning with ATT&CK technique T1059 for command and scripting interpreter and T1190 for exploit public-facing application.