CVE-2013-4478 in Sup
Summary
by MITRE
Sup before 0.13.2.1 and 0.14.x before 0.14.1.1 allows remote attackers to execute arbitrary commands via shell metacharacters in the filename of an email attachment.
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Analysis
by VulDB Data Team • 01/11/2022
The vulnerability identified as CVE-2013-4478 affects the sup email client software, specifically versions prior to 0.13.2.1 and 0.14.x versions before 0.14.1.1. This represents a critical command injection flaw that enables remote attackers to execute arbitrary system commands through carefully crafted email attachments. The vulnerability stems from insufficient input validation and sanitization within the email processing pipeline, particularly when handling filenames of email attachments.
The technical implementation of this vulnerability occurs when the sup client processes email attachments and fails to properly escape or filter shell metacharacters present in attachment filenames. When an attacker crafts a malicious email with an attachment name containing special shell characters such as semicolons, pipes, or command substitutions, the client's processing routine interprets these characters as command delimiters or operators rather than literal filename characters. This improper handling creates a command injection vector where attacker-controlled commands can be executed with the privileges of the user running the sup client.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise. An attacker who successfully exploits this vulnerability can gain unauthorized access to the victim's system, potentially leading to data exfiltration, persistence mechanisms, or further network reconnaissance. The remote nature of the attack means that victims need not interact with the malicious email for exploitation to occur, as the command injection can be triggered during the automatic processing of email attachments. This vulnerability particularly affects environments where users regularly process emails from untrusted sources or where automated email handling systems are in place.
Security professionals should recognize this vulnerability as a classic example of command injection flaws that align with CWE-77 and CWE-88 categories, representing improper neutralization of special elements used in command execution. The attack pattern follows established techniques documented in the MITRE ATT&CK framework under the T1059.001 sub-technique for command and scripting interpreter. Organizations should implement immediate mitigations including upgrading to patched versions of the sup client, implementing email filtering rules to block suspicious attachment names, and deploying network-based intrusion detection systems to monitor for exploitation attempts. Additionally, user education regarding the dangers of opening email attachments from unknown sources remains critical in reducing the attack surface for this and similar vulnerabilities.