CVE-2023-40053 in Serv-U
Summary
by MITRE • 12/06/2023
A vulnerability has been identified within Serv-U 15.4 that allows an authenticated actor to insert content on the file share function feature of Serv-U, which could be used maliciously.
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Analysis
by VulDB Data Team • 12/24/2023
The vulnerability identified as CVE-2023-40053 resides within the Serv-U file sharing software version 15.4, specifically targeting the file share function feature. This represents a critical security flaw that enables authenticated attackers to inject malicious content into the file sharing system, potentially compromising the integrity and confidentiality of shared data. The issue manifests when legitimate users with valid credentials attempt to utilize the file sharing capabilities, creating a pathway for unauthorized content insertion that could be exploited for various malicious purposes.
This vulnerability stems from insufficient input validation and sanitization mechanisms within the file share function implementation. The flaw allows an authenticated user to manipulate the content being uploaded or shared through the system, potentially introducing malicious files or modifying existing content in ways that could disrupt normal operations or compromise system security. The technical nature of this vulnerability aligns with CWE-79, which describes cross-site scripting flaws, and CWE-20, which covers improper input validation issues. The root cause likely involves inadequate filtering of user-supplied data before it is processed or stored within the file sharing system.
The operational impact of this vulnerability extends beyond simple content manipulation, as it creates potential vectors for more sophisticated attacks including malware distribution, data exfiltration, and system compromise. An attacker could leverage this flaw to upload malicious files that might execute upon access by other users, establish persistence mechanisms, or serve as a foothold for further exploitation. The authenticated nature of the attack means that even a limited user account could potentially cause significant damage within the file sharing environment, making this vulnerability particularly concerning for organizations that rely heavily on shared file systems for business operations. This weakness directly impacts the principle of least privilege and could enable privilege escalation scenarios within the file sharing context.
Organizations utilizing Serv-U 15.4 should prioritize immediate remediation through official vendor patches or updates to address this vulnerability. The mitigation strategy should include implementing network segmentation to limit access to file sharing functions, enforcing strict access controls and monitoring user activities within the file sharing system, and conducting thorough audits of shared content to identify any potential malicious modifications. Security teams should also consider deploying content inspection tools that can detect and prevent malicious file uploads, while implementing comprehensive logging and monitoring of file sharing activities to identify anomalous behavior. The vulnerability demonstrates the importance of proper input validation and sanitization as outlined in the OWASP Top Ten and aligns with ATT&CK technique T1078 for valid accounts and T1566 for spearphishing with attachments, emphasizing the need for layered security approaches to protect file sharing environments.