ALIASES:

Trojan:Win32/Skeeyah.A!rfn (Microsoft); Backdoor.Emdivi!gen1 (Symantec); BehavesLike.Win32.Malware.wlk (mx-v) (Sunbelt); Found Win32/DH{gRKBEyAeDyJbJQ} (AVG)

 PLATFORM:

Windows

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

  • 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.

  TECHNICAL DETAILS

File Size: 207,360 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 Jun 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.

Autostart Technique

This backdoor modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,{malware path and file name},"

(Note: The default value data of the said registry entry is %Windows%\system32\userinit.exe,.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://www.{BLOCKED}g.com
  • http://www.{BLOCKED}g.com/sites.php

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.750

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 delete files detected as BKDR_EMDIVI.YUP using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\userinit.exe,{malware path and file name},"
      To: Userinit = ""%Windows%\system32\userinit.exe,""

Step 4

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