Analysis by: Sammy Chua
ALIASES:

Backdoor:PHP/SimpleShell.A (Microsoft);Backdoor.PHP.C99Shell.ir (Kaspersky); Troj/PHPShl-AK (Sophos)

 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 arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be hosted on a website and run when a user accesses the said website.

  TECHNICAL DETAILS

File Size: 1,515 bytes
File Type: Script
Initial Samples Received Date: 13 Apr 2015

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

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

Installation

This backdoor drops the following files:

  • {document root directory where the script is executing}/images/stories/food/footer.php

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.632.04
FIRST VSAPI PATTERN DATE: 27 Apr 2015
VSAPI OPR PATTERN File: 11.633.00
VSAPI OPR PATTERN Date: 28 Apr 2015

Step 1

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 2

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

Step 3

Search and delete this file

[ 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.
  • {document root folder where script executes}/images/stories/food/footer.php

Step 4

Scan your computer with your Trend Micro product to delete files detected as PHP_SIMPLESHELL.E. 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.


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