false positives may occur depending on the web server's configuration. if the web server is intentionally configured to utilize the remote shellservlet, then the detections by this analytic would not be considered true positives.

Techniques

T1190

Sample rules

Web Remote ShellServlet Access

source: splunk
technicques:
- T1190

Description

This analytic identifies attempts to access the Remote ShellServlet on a web server, which is utilized to execute commands. Such activity is commonly linked with web shells and other forms of malicious behavior. It was specifically detected on a Confluence server in relation to CVE-2023-22518 and CVE-2023-22515. Activities preceding access to the shell servlet include the addition of a plugin to Confluence. Additionally, it is advisable to monitor for ShellServlet?act=3, ShellServlet, or obfuscated variations such as Sh3llServlet1.

Detection logic


| tstats count min(_time) as firstTime max(_time) as lastTime from datamodel=Web where Web.url IN ("*plugins/servlet/com.jsos.shell/*") Web.status=200 by Web.http_user_agent, Web.status Web.http_method, Web.url, Web.url_length, Web.src, Web.dest, sourcetype 
| `drop_dm_object_name("Web")` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `web_remote_shellservlet_access_filter`