ALIASES:

Backdoor.PHP.C99Shell.p (Kaspersky), Backdoor.PHP.C99Shell.B (F-Secure)

 PLATFORM:

Windows, Linux, Unix

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

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

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: Varies
File Type: Script
Initial Samples Received Date: 06 Oct 2014
Payload: Displays UI

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

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Upload/download files to/from the web server
  • Detect available drives on the system
  • List files and folders
  • Provide user full access to files and folders
  • Search files with specific contents
  • Create file and folder
  • View file and folder information
  • Execute shell commands
  • View list of processes running on the system
  • Bind standard input/output of the command interpreter to assigned TCP port
  • Bind standard input/ output of the command interpreter to data from certain IRC server (Datapipe)
  • Manage SQL databases
  • Execute PHP code
  • Remove itself from the server
  • Scan FTP accounts for weak passwords using brute force and log them to file and e-mail

NOTES:

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 the following GUI:

  SOLUTION

Minimum Scan Engine: 9.700

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

Scan your computer with your Trend Micro product to delete files detected as PHP_C99SHELL.SM. 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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