CVE-2019-19829 in Serv-U FTP Server
Summary
by MITRE
A cross-site scripting (XSS) vulnerability exists in SolarWinds Serv-U FTP Server 15.1.7 in the email parameter, a different vulnerability than CVE-2018-19934 and CVE-2019-13182.
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Analysis
by VulDB Data Team • 03/15/2024
The cross-site scripting vulnerability identified as CVE-2019-19829 represents a critical security flaw within the SolarWinds Serv-U FTP Server version 15.1.7 that specifically affects the email parameter handling functionality. This vulnerability falls under the broader category of web application security issues that can compromise user sessions and potentially lead to unauthorized access or data exfiltration. The flaw manifests when the application fails to properly sanitize or validate user-supplied input through the email parameter, creating an avenue for malicious actors to inject arbitrary JavaScript code into web responses. Unlike similar vulnerabilities such as CVE-2018-19934 and CVE-2019-13182 which affect different components of the same software suite, this particular XSS vulnerability is isolated to the email parameter processing within the Serv-U FTP server's web interface. The vulnerability is classified under CWE-79 which specifically addresses Cross-Site Scripting flaws in web applications, where improper validation of user input allows malicious scripts to be executed in the context of other users' browsers.
The technical exploitation of this vulnerability requires an attacker to craft a malicious payload that includes JavaScript code within the email parameter when submitting data through the affected service. When the vulnerable application processes this input without adequate sanitization, the malicious script becomes embedded within the web response and subsequently executed in the browser of any user who views the affected page or interacts with the compromised data. The operational impact extends beyond simple script execution as this vulnerability can enable session hijacking, credential theft, and potential lateral movement within network environments where the affected FTP server is deployed. Attackers could leverage this flaw to establish persistent access to the system by injecting scripts that capture user credentials or redirect users to malicious sites. The vulnerability particularly affects environments where the Serv-U FTP server's web administration interface is exposed to untrusted users or where administrators may inadvertently interact with compromised web pages.
Organizations utilizing SolarWinds Serv-U FTP Server version 15.1.7 should implement immediate mitigations to protect against exploitation of this XSS vulnerability. The primary defense mechanism involves implementing proper input validation and output encoding for all user-supplied data, particularly within the email parameter handling functionality. Security teams should deploy web application firewalls that can detect and block malicious script payloads attempting to exploit this vulnerability. Additionally, implementing content security policies that restrict script execution and enforcing strict input sanitization measures will significantly reduce the attack surface. The vulnerability aligns with several ATT&CK techniques including T1059.007 for command and scripting interpreter and T1566 for credential harvesting through social engineering approaches that leverage XSS flaws. Organizations should also consider restricting access to the web administration interface to trusted IP addresses only and implementing multi-factor authentication to add additional layers of protection. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities within the broader application ecosystem, as this flaw demonstrates the importance of comprehensive input validation across all user-facing parameters in enterprise FTP solutions.