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BKDR_INJECT.EJSH

December 15, 2014
 Analysis by: Cris Nowell Pantanilla
 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


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 connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible. It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

494592 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Dec 2014

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 drops the following copies of itself into the affected system and executes them:

  • %SYSTEM%\dnsaels.exe

It injects codes into the following process(es):

  • explorer.exe

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
camosapi = %SYSTEM%\dnsaels.exe

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\AppDataLow\
F852C40F-F7F9-EA0E-41AC-1BBE05A07FD2

Other Details

This backdoor connects to the following website to send and receive information:

  • {BLOCKED}omter.su
  • {BLOCKED}orjution.su
  • {BLOCKED}perkom.com

However, as of this writing, the said sites are inaccessible.

It deletes the initially executed copy of itself

NOTES:

This backdoor is capable of the following:

  • Get system information
  • Get cookies and browser profiles
  • Get running process/services
  • Get installed drivers
  • Get installed programs
  • Connect to remote site
  • Download/Upload file
  • Execute commands

  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

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • F852C40F-F7F9-EA0E-41AC-1BBE05A07FD2

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • camosapi = "%SYSTEM%\dnsaels.exe"

Step 4

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