PHP_WEBSHELL.XUW

March 17, 2016
 Analysis by: Pearl Charlaine Espejo
 ALIASES:

PHP.Backdoor.Trojan (Symantec); Backdoor.PHP.Agent.ym (Kaspersky); PHP/BackDoor.gen.c (McAfee); Backdoor:PHP/SimpleShell.A (Microsoft)

 PLATFORM:

Windows, Linux

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor may be hosted on a website and run when a user accesses the said website.

  TECHNICAL DETAILS

File Size:

28,863 bytes

File Type:

Script

Memory Resident:

No

Initial Samples Received Date:

09 Feb 2016

Arrival Details

This backdoor may be hosted on a website and run when a user accesses the said website.

This malware arrives via the following means:

  • May be uploaded and installed on a web server by a remote malicious user after gaining access to the server.

Other System Modifications

This backdoor deletes the following files:

  • {malware parent directory}/revslider.zip

Dropping Routine

This backdoor drops the following files:

  • {PHP Server document root}/en.php
  • {PHP Server document root}/wp-includes/jahat.php
  • {PHP Server document root}/wp-indeks.php
  • {PHP Server document root}/wp-includes/routing.php

NOTES:

This malware modifies, if the files are existing, or creates the following files:

  • {PHP Server document root}/wp-content/themes/Avada/framework/plugins/revslider/temp/.htaccess
  • {PHP Server document root}/wp-content/plugins/revslider/temp/.htaccess
  • {malware current directory}/.htaccess

Once this PHP script is installed, the user may then launch a backdoor on the affected system.

Opening the page, the malicious user is shown a GUI for its malicious routines.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.328.02

FIRST VSAPI PATTERN DATE:

09 Feb 2016

VSAPI OPR PATTERN File:

12.329.00

VSAPI OPR PATTERN Date:

10 Feb 2016

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Close all opened browser windows

Step 3

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.  
  • {PHP Server document root}/en.php
  • {PHP Server document root}/wp-includes/jahat.php
  • {PHP Server document root}/wp-indeks.php
  • {PHP Server document root}/wp-includes/routing.php

Step 4

Scan your computer with your Trend Micro product to delete files detected as PHP_WEBSHELL.XUW. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 5

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • {PHP Server document root}/wp-content/themes/Avada/framework/plugins/revslider/temp/.htaccess
  • {PHP Server document root}/wp-content/plugins/revslider/temp/.htaccess
  • {malware current directory}/.htaccess
  • {malware parent directory}/revslider.zip


Did this description help? Tell us how we did.