CVE-2020-15575 in Serv-U File Server
Summary
by MITRE
SolarWinds Serv-U File Server before 15.2.1 allows XSS as demonstrated by Tenable Scan, aka Case Number 00484194.
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Analysis
by VulDB Data Team • 10/29/2020
The vulnerability identified as CVE-2020-15575 represents a cross-site scripting flaw within SolarWinds Serv-U File Server versions prior to 15.2.1. This vulnerability was discovered through Tenable Scan analysis and subsequently documented under case number 00484194, highlighting the critical nature of web application security in enterprise file transfer solutions. The flaw specifically manifests in the web interface of the Serv-U server, which is commonly used for secure file transfers and management across organizations.
The technical implementation of this XSS vulnerability stems from insufficient input validation and output encoding within the web-based administration interface of Serv-U. Attackers can exploit this weakness by injecting malicious script code into parameters that are subsequently rendered in web pages without proper sanitization. The vulnerability falls under CWE-79, which specifically addresses Cross-Site Scripting flaws, and represents a classic example of how web applications fail to properly escape user-controllable data before incorporating it into dynamically generated HTML content. The flaw allows attackers to execute arbitrary JavaScript code in the context of a victim's browser session, potentially leading to full compromise of the affected system.
The operational impact of this vulnerability extends beyond simple script injection, as it can be leveraged for more sophisticated attacks including session hijacking, credential theft, and privilege escalation within the Serv-U environment. Security researchers noted that the vulnerability could be exploited by unauthenticated attackers, making it particularly dangerous in environments where the Serv-U web interface is accessible from external networks. The exploitation chain typically involves crafting malicious payloads that target specific input fields within the web administration console, where the reflected or stored scripts are executed when legitimate users view affected pages. This vulnerability directly aligns with ATT&CK technique T1566.001, which covers credential harvesting through spearphishing attachments and links.
Organizations utilizing SolarWinds Serv-U File Server versions prior to 15.2.1 should immediately implement mitigations including patching to the latest version, which contains proper input validation and output encoding mechanisms. Network segmentation strategies should be employed to limit access to the web administration interface, while implementing web application firewalls to detect and block suspicious script injection attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches in enterprise environments, particularly for applications that serve as central points of access for file transfer operations. Security teams should also conduct thorough penetration testing to identify similar vulnerabilities in other web-based enterprise applications and establish robust monitoring procedures to detect potential exploitation attempts.