CVE-2018-8741 in SquirrelMail
Summary
by MITRE
A directory traversal flaw in SquirrelMail 1.4.22 allows an authenticated attacker to exfiltrate (or potentially delete) files from the hosting server, related to ../ in the att_local_name field in Deliver.class.php.
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Analysis
by VulDB Data Team • 02/22/2023
The vulnerability identified as CVE-2018-8741 represents a critical directory traversal flaw within the SquirrelMail webmail application version 1.4.22. This security weakness resides in the Deliver.class.php file where the att_local_name field fails to properly sanitize user input containing directory traversal sequences such as ../. The flaw enables authenticated attackers who have gained access to a valid user account to exploit this vulnerability and potentially access or manipulate files on the underlying server filesystem. The vulnerability stems from insufficient input validation and sanitization mechanisms that should have prevented malicious path traversal sequences from being processed as legitimate file references. This type of vulnerability falls under the CWE-22 category, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The attack vector requires an authenticated user context, meaning that an attacker must first obtain valid login credentials before exploiting this weakness, which reduces the attack surface but does not eliminate the severity of the potential impact.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious input containing directory traversal sequences within the att_local_name parameter during email attachment handling operations. When the application processes this malformed input without proper sanitization, it allows the attacker to navigate outside the intended directory structure and access files that should remain restricted. This could potentially lead to the exfiltration of sensitive configuration files, user data, or even system files that contain credentials or other confidential information. The impact extends beyond mere data theft as the vulnerability could also enable attackers to delete or overwrite critical files on the server, potentially causing system instability or complete service disruption. The flaw demonstrates poor input validation practices that violate fundamental security principles for handling user-supplied data, particularly in web applications where user input can be used to influence file system operations.
The operational impact of CVE-2018-8741 extends beyond immediate data compromise to include potential system compromise and broader security implications for organizations relying on SquirrelMail for email services. Organizations using vulnerable versions of SquirrelMail face significant risk of unauthorized file access, which could expose sensitive corporate data, user credentials, or application configuration details. The authenticated nature of the attack means that attackers typically need to compromise at least one valid user account, but this requirement does not prevent the vulnerability from being exploited at scale if multiple accounts are compromised. The vulnerability also represents a potential stepping stone for further attacks, as access to server files could provide attackers with information needed to escalate privileges or move laterally within the network infrastructure. This type of vulnerability aligns with ATT&CK technique T1083 which covers File and Directory Discovery, and T1078 which addresses Valid Accounts, demonstrating how directory traversal flaws can be leveraged as part of broader attack chains.
Mitigation strategies for CVE-2018-8741 should focus on immediate patching of the SquirrelMail application to version 1.4.23 or later, which contains the necessary fixes for this directory traversal vulnerability. Organizations should also implement additional security controls such as input validation at multiple layers, including application-level sanitization of user-supplied data before it is processed in file system operations. Network segmentation and access controls should be reviewed to limit the potential impact of compromised accounts, while monitoring systems should be configured to detect unusual file access patterns that might indicate exploitation attempts. Security teams should also consider implementing web application firewalls that can detect and block malicious path traversal sequences, and regular security assessments should be conducted to identify similar vulnerabilities in other web applications. The vulnerability serves as a reminder of the critical importance of proper input validation and the principle of least privilege in web application security, where all user-supplied data should be treated as potentially malicious and validated accordingly. Organizations should also maintain up-to-date inventory of all web applications and services to ensure timely patch management and vulnerability remediation across their entire infrastructure.