sigmahighHunting

Webshell ReGeorg Detection Via Web Logs

Certain strings in the uri_query field when combined with null referer and null user agent can indicate activity associated with the webshell ReGeorg.

MITRE ATT&CK

T1505.003

persistence

Detection Query

selection:
  cs-uri-query|contains:
    - cmd=read
    - connect&target
    - cmd=connect
    - cmd=disconnect
    - cmd=forward
filter:
  cs-referer: null
  cs-user-agent: null
  cs-method: POST
condition: selection and filter

Author

Cian Heasley

Created

2020-08-04

Data Sources

webserver

References

Tags

attack.persistenceattack.t1505.003

Raw Content

title: Webshell ReGeorg Detection Via Web Logs
id: 2ea44a60-cfda-11ea-87d0-0242ac130003
status: test
description: Certain strings in the uri_query field when combined with null referer and null user agent can indicate activity associated with the webshell ReGeorg.
references:
    - https://community.rsa.com/community/products/netwitness/blog/2019/02/19/web-shells-and-netwitness-part-3
    - https://github.com/sensepost/reGeorg
author: Cian Heasley
date: 2020-08-04
modified: 2023-01-02
tags:
    - attack.persistence
    - attack.t1505.003
logsource:
    category: webserver
detection:
    selection:
        cs-uri-query|contains:
            - 'cmd=read'
            - 'connect&target'
            - 'cmd=connect'
            - 'cmd=disconnect'
            - 'cmd=forward'
    filter:
        cs-referer: null
        cs-user-agent: null
        cs-method: POST
    condition: selection and filter
falsepositives:
    - Web applications that use the same URL parameters as ReGeorg
level: high