CVE-2018-14354 in Mutt
Summary
by MITRE
An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16. They allow remote IMAP servers to execute arbitrary commands via backquote characters, related to the mailboxes command associated with a manual subscription or unsubscription.
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Analysis
by VulDB Data Team • 04/09/2023
The vulnerability identified as CVE-2018-14354 represents a critical command injection flaw affecting Mutt and NeoMutt email clients prior to specific version releases. This security issue stems from improper handling of backquote characters within IMAP server responses during mailbox subscription and unsubscription operations. The flaw exists in the client-side parsing logic that processes mailbox names and commands returned by remote IMAP servers, creating an avenue for remote code execution through maliciously crafted server responses.
The technical implementation of this vulnerability resides in the mailboxes command processing within the Mutt and NeoMutt email clients. When users interact with IMAP servers through these clients, the software executes a mailboxes command to manage mailbox subscriptions. The vulnerability occurs when the client encounters backquote characters in mailbox names returned by the server, which are then interpreted as command delimiters rather than literal characters. This misinterpretation allows remote IMAP servers to inject arbitrary commands that get executed within the context of the email client process, effectively bypassing normal security boundaries.
From an operational perspective, this vulnerability presents significant risks to users who connect to untrusted or compromised IMAP servers. Attackers can exploit this flaw by hosting malicious IMAP servers that return specially crafted mailbox names containing backquote characters followed by malicious commands. When users perform subscription or unsubscription operations, the client automatically processes these responses, executing the injected commands without user intervention. The impact extends beyond simple command execution to potentially allow full system compromise, data exfiltration, or further attack vector establishment.
The vulnerability maps to CWE-78, which specifically addresses "Improper Neutralization of Special Elements used in OS Command" and aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter. This classification indicates the flaw enables adversaries to execute arbitrary code through legitimate system interfaces, making it particularly dangerous in enterprise environments where users may connect to various IMAP servers including those hosted by third parties or potentially compromised entities. The vulnerability demonstrates how seemingly benign client-side parsing logic can create significant security risks when dealing with untrusted remote inputs.
Mitigation strategies for CVE-2018-14354 involve immediate upgrading to Mutt version 1.10.1 or NeoMutt version 2018-07-16 and later, which contain patches addressing the backquote character handling. Organizations should also implement network segmentation to limit access to trusted IMAP servers, deploy monitoring solutions to detect unusual command execution patterns, and educate users about the risks of connecting to untrusted email servers. Additional protective measures include configuring email clients to disable automatic subscription management features and implementing strict input validation for mailbox names to prevent command injection scenarios. The vulnerability highlights the importance of proper input sanitization in client applications that interact with remote servers and demonstrates how protocol-level flaws can be exploited to achieve system compromise.