title: Antivirus Web Shell Detection
author: Florian Roth, Arnim Rupp
date: 2018/09/09
description: Detects a highly relevant Antivirus alert that reports a web shell. It's
  highly recommended to tune this rule to the specific strings used by your anti virus
  solution by downloading a big webshell repo from e.g. github and checking the matches.
detection:
  SELECTION_1:
    Signature:
    - PHP/*
    - JSP/*
    - ASP/*
    - Perl/*
    - PHP.*
    - JSP.*
    - ASP.*
    - Perl.*
    - VBS/Uxor*
    - IIS/BackDoor*
    - JAVA/Backdoor*
    - Troj/ASP*
    - Troj/PHP*
    - Troj/JSP*
  SELECTION_2:
    Signature:
    - '*Webshell*'
    - '*Chopper*'
    - '*SinoChoper*'
    - '*ASPXSpy*'
    - '*Aspdoor*'
    - '*filebrowser*'
    - '*PHP_*'
    - '*JSP_*'
    - '*ASP_*'
    - '*PHP:*'
    - '*JSP:*'
    - '*ASP:*'
    - '*Perl:*'
    - '*PHPShell*'
    - '*Trojan.PHP*'
    - '*Trojan.ASP*'
    - '*Trojan.JSP*'
    - '*Trojan.VBS*'
    - '*PHP?Agent*'
    - '*ASP?Agent*'
    - '*JSP?Agent*'
    - '*VBS?Agent*'
    - '*Backdoor?PHP*'
    - '*Backdoor?JSP*'
    - '*Backdoor?ASP*'
    - '*Backdoor?VBS*'
    - '*Backdoor?Java*'
  condition: (SELECTION_1 or SELECTION_2)
falsepositives:
- Unlikely
fields:
- FileName
- User
id: fdf135a2-9241-4f96-a114-bb404948f736
level: critical
logsource:
  product: antivirus
modified: 2021/05/08
references:
- https://www.nextron-systems.com/2021/03/25/antivirus-event-analysis-cheat-sheet-v1-8/
- https://github.com/tennc/webshell
- https://www.virustotal.com/gui/file/bd1d52289203866645e556e2766a21d2275877fbafa056a76fe0cf884b7f8819/detection
- https://www.virustotal.com/gui/file/308487ed28a3d9abc1fec7ebc812d4b5c07ab025037535421f64c60d3887a3e8/detection
- https://www.virustotal.com/gui/file/7d3cb8a8ff28f82b07f382789247329ad2d7782a72dde9867941f13266310c80/detection
- https://www.virustotal.com/gui/file/e841675a4b82250c75273ebf0861245f80c6a1c3d5803c2d995d9d3b18d5c4b5/detection
- https://www.virustotal.com/gui/file/a80042c61a0372eaa0c2c1e831adf0d13ef09feaf71d1d20b216156269045801/detection
- https://www.virustotal.com/gui/file/b219f7d3c26f8bad7e175934cd5eda4ddb5e3983503e94ff07d39c0666821b7e/detection
- https://www.virustotal.com/gui/file/b8702acf32fd651af9f809ed42d15135f842788cd98d81a8e1b154ee2a2b76a2/detection
status: experimental
tags:
- attack.persistence
- attack.t1100
- attack.t1505.003
ruletype: SIGMA