BKDR_ZEGOST.YNNY

July 15, 2014
 ALIASES:

Backdoor:Win32/Zegost.BX (Microsoft); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse BackDoor.Generic_r.EWW (AVG)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

278,528 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

15 Jul 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:

  • %Windows%\Oekieyo.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

Autostart Technique

This backdoor registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Ruysdi wswmpeat

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Cnnvsy kahrma

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ruysdi wswmpeat
ReleiceName = "Cnnvsy kahrma"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Cnnvsy kahrma
ConnectGroup = "ĬÈÏ·Ö×é"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Cnnvsy kahrma
MarkTime = "2014-06-24 20:07"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Cnnvsy kahrma
Description = "Aeeyoh yyqqeakw ucnhcumarwc"

Dropping Routine

This backdoor drops the following files:

  • %System Root%\3054.vbs

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://xxx.{BLOCKED}8.com
  • {BLOCKED}.46.73
  • {BLOCKED}0.1
  • {BLOCKED}.8.107
  • {BLOCKED}.15.115

It deletes itself after execution.

This report is generated via an automated analysis system.

  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

Restart in Safe Mode

[ Learn More ]

Step 3

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Ruysdi wswmpeat
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Cnnvsy kahrma

Step 4

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_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Ruysdi wswmpeat
    • ReleiceName = "Cnnvsy kahrma"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Cnnvsy kahrma
    • ConnectGroup = "ĬÈÏ·Ö×é"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Cnnvsy kahrma
    • MarkTime = "2014-06-24 20:07"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Cnnvsy kahrma
    • Description = "Aeeyoh yyqqeakw ucnhcumarwc"

Step 5

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %System Root%\3054.vbs

Step 6

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