SID 1:64004

Rule Category

SERVER-WEBAPP -- Snort has detected traffic exploiting vulnerabilities in web based applications on servers.

Alert Message

SERVER-WEBAPP Draytek VigorConnect directory traversal attempt

Rule Explanation

This rule looks for path traversal sequences present in the following parameters in HTTP requests sent to the /ACSServer/DownloadFileServlet endpoint on Draytek VigorConnect web applications: show_file_name.

What To Look For

This rule looks for attempts to exploit a directory traversal vulnerability in Draytek VigorConnect web applications.

Known Usage

Public information/Proof of Concept available

False Positives

No known false positives

Contributors

Cisco Talos Intelligence Group

Rule Groups

Rule Categories::Server::Web Applications

MITRE::ATT&CK Framework::Enterprise::Initial Access::Exploit Public-Facing Application

Adversaries may attempt to take advantage of a weakness in an Internet-facing computer or program using software, data, or commands in order to cause unintended or unanticipated behavior. The weakness in the system can be a bug, a glitch, or a design vulnerability. These applications are often websites, but can include databases (like SQL), standard services (like SMB or SSH), network device administration and management protocols (like SNMP and Smart Install), and any other applications with Internet accessible open sockets, such as web servers and related services.

CVE

CVE-2021-20123

Additional Links

www.tenable.com/security/research/tra-2021-42

Rule Vulnerability

Directory Traversal

A Directory Traversal attack targets HTTP traffic and allows the attacker to access directories outside the applications own, potentially exposing sensitive system files to leakage or overwriting. This is also known as Directory Climbing, Path Traversal, or Backtracking. An alert on this kind of attack indicates a vulnerability in security validation of user input that allows a "traverse to parent directory" or "../" command to pass through. Protect your site by filtering all user input, removing any characters but the allowed data.

CVE Additional Information

This product uses data from the NVD API but is not endorsed or certified by the NVD.

CVE-2021-20123

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