CVE-2018-14355 in Mutt
Summary
by MITRE
An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16. imap/util.c mishandles ".." directory traversal in a mailbox name.
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Analysis
by VulDB Data Team • 04/09/2023
The vulnerability identified as CVE-2018-14355 represents a critical directory traversal flaw affecting Mutt and NeoMutt email clients prior to their respective security updates. This issue resides within the imap/util.c component of these email applications, where the software fails to properly sanitize mailbox names containing ".." sequences that could potentially be exploited to access unintended directories on the system. The flaw manifests when the application processes mailbox names that include directory traversal sequences, creating a pathway for malicious actors to navigate beyond the intended mail storage locations. This vulnerability directly impacts the security model of these email clients by potentially allowing unauthorized access to files and directories that should remain isolated from user mail operations.
The technical implementation of this vulnerability stems from inadequate input validation within the IMAP protocol handling functionality of the email clients. When processing mailbox names that contain ".." sequences, the application does not properly validate or sanitize these paths before attempting to access the corresponding directories on the filesystem. This weakness allows an attacker to craft specially formatted mailbox names that, when processed by the vulnerable software, could result in directory traversal attacks. The flaw specifically affects the handling of IMAP mailbox names where the double dot notation is used to reference parent directories, bypassing normal path validation mechanisms. This represents a classic path traversal vulnerability that aligns with CWE-22, which defines the weakness as improper limitation of a pathname to a restricted directory, commonly known as directory traversal or path traversal. The vulnerability operates at the application layer and can be exploited through the IMAP protocol, making it particularly dangerous in environments where email clients connect to remote mail servers.
The operational impact of CVE-2018-14355 extends beyond simple unauthorized file access, potentially enabling attackers to execute arbitrary code or escalate privileges within the context of the email client process. An attacker could exploit this vulnerability to access sensitive configuration files, authentication credentials, or other system resources that are not properly isolated from the mail handling process. The risk is particularly elevated in multi-user environments or when email clients are configured to access remote mail servers with elevated privileges. This vulnerability can be leveraged to gain insights into the underlying system structure, potentially exposing information that could aid in further exploitation attempts. The impact is consistent with ATT&CK technique T1059.007, which involves the use of command and scripting interpreter for execution, as the vulnerability could enable an attacker to access system resources that might contain command execution capabilities. The flaw essentially undermines the security boundaries that should exist between the email client application and the underlying filesystem.
Mitigation strategies for CVE-2018-14355 primarily involve upgrading to patched versions of Mutt or NeoMutt where the directory traversal handling has been corrected. Users should immediately update to Mutt version 1.10.1 or later, or NeoMutt versions released after July 16, 2018, which contain the necessary fixes for this vulnerability. Organizations should also implement network segmentation to limit access to mail servers and ensure that email clients are not configured with unnecessary privileges when connecting to IMAP servers. Additional protective measures include monitoring IMAP traffic for suspicious mailbox name patterns and implementing strict access controls on mail storage directories. Security teams should also consider disabling IMAP functionality when it is not required or when the risk of exploitation is high, particularly in environments where the email clients handle sensitive data. The vulnerability serves as a reminder of the importance of proper input validation and the need for robust security testing of protocol handling components in email applications.