BKDR_EMDIVI.TRYL

 Analysis by: RonJay Kristoffer Caragay

 ALIASES:

Backdoor.Win32.Emdivi.l (Kaspersky); 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 does not have any propagation routine.

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

It retrieves specific information from the affected system.

  TECHNICAL DETAILS

File Size:

438,272 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

20 Aug 2015

Payload:

Connects to URLs/IPs, Steals information

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.

Installation

This backdoor adds the following mutexes to ensure that only one of its copies runs at any one time:

  • 51d2127a118abf444eff7f54285e8f8e

Propagation

This backdoor does not have any propagation routine.

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
  • Choose HTTP Authentication
  • Setup Proxy auto-configuration
  • Gather Firefox settings from prefs.js
  • Gather proxy settings from proxy.pac
  • Gather proxy settings from windows registry
  • Clear Security Event Logs
  • Sleep

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

  • http://www.{BLOCKED}l.epac.to/index.php
  • http://{BLOCKED}o.softether.net/index{2 random numbers}.html
  • http://{BLOCKED}p.ninjia.org/index{2 random numbers}.html
  • http://{BLOCKED}8.wariskind.com

Information Theft

This backdoor retrieves the following information from the affected system:

  • Host name
  • Process ID of the malware
  • Memory Size (RAM)
  • Internet Explorer Version
  • Windows OS Version
  • System Language
  • Location
  • Time Zone Information

Other Details

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

  • http://www.msftncsi.com/ncsi.txt
  • http://www.microsoft.com/en-us/default.aspx
  • http://www.yahoo.co.jp

NOTES:

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

  • OllyDbg
  • W32Dasm
  • Wireshark
  • Fiddler
  • SoftICE
  • Process Explorer
  • Process Monitor
  • Process Hacker

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

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.866.04

FIRST VSAPI PATTERN DATE:

20 Aug 2015

VSAPI OPR PATTERN File:

11.867.00

VSAPI OPR PATTERN Date:

21 Aug 2015

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

Identify and terminate files detected as BKDR_EMDIVI.TRYL

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR_EMDIVI.TRYL. 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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