BKDR_EMDIVI.XX

December 14, 2014
 Analysis by: Jaime Benigno Reyes
 ALIASES:

Backdoor.Emdivi!gen1 (Symantec)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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

  TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Dec 2014

Payload:

Connects to URLs/IPs, Compromises system security

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.

Backdoor Routine

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

  • Enumerate files and folders
  • Delete files and folders
  • Download files
  • Upload files
  • Execute files
  • Get file attributes
  • Enumerate processes
  • Perform remote shell
  • Loads a library using LoadLibrary API
  • Import functions from a library using GetProcAddress API
  • Gather credentials using CredEnumerate or PStoreCreateInstance API
  • Gather Firefox settings from prefs.js
  • Gather proxy settings from proxy.pac
  • Gather proxy settings from windows registry
  • Sleep

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://www.{BLOCKED}me.com/{5-digit number}.html
  • http://www.{BLOCKED}tion.com/{4-digit number}.html
  • http://www.{BLOCKED}o.jp/{4-digit number}.html
  • http://www.{BLOCKED}o.jp/{4-digit number}.html
  • http://www.{blocked}s.co.jp/{4-digit number}.html

As of this writing, the said sites are inaccessible.

Other Details

This backdoor connects to the following URL(s) to check for an Internet connection:

  • http://www.microsoft.com
  • http://www.msftncsi.com
  • http://www.yahoo.co.jp

NOTES:

It enumerates all visible windows and compares each window's title bar text with the following strings:

  • Ollydbg
  • Process Explorer
  • Process Hacker
  • Process Monitor
  • SoftICE
  • W32Dasm
  • WireShark

If a window's title bar text contains any of the said strings, it will pause the execution of its malicious routine by performing a Sleep command.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.320.01

FIRST VSAPI PATTERN DATE:

04 Dec 2014

VSAPI OPR PATTERN File:

11.321.00

VSAPI OPR PATTERN Date:

05 Dec 2014

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 and note files detected as BKDR_EMDIVI.XX

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete files detected as BKDR_EMDIVI.XX

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_EMDIVI.XX. 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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