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BKDR_ZEGOST.YN

June 28, 2014
 Modified by: RonJay Kristoffer Caragay
 ALIASES:

Backdoor:Win32/Zegost.BZ(Microsoft), BDS/Zegost.BZ.226(AntiVir), Virus.Win32.Dialer(Ikarus)

 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:
 INFORMATION EXPOSURE:

  • 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 registry entries, causing some applications and programs to not function properly.

  TECHNICAL DETAILS

File Size:

168,061 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

26 Jun 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.

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
x7 = "{malware path and file name}"

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Hardware Profiles\Current\System\
CurrentControlSet\Enum\PCI\
VEN_{value1}&DEV_{value2}&SUBSYS_{value3}&REV_{value4}\{value}
CSConfigFlags = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\PCI\VEN_{value1}&DEV_{value2}&SUBSYS_{value3}&REV_{value4}\
{value}\Control
DisableCount = "0"

It deletes the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\PCI\VEN_{value1}&DEV_{value2}&SUBSYS_{value3}&REV_{value4}\
{value}\LogConf
BootConfig = {hex values}

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}2014.f3322.org

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.886.04

FIRST VSAPI PATTERN DATE:

26 Jun 2014

VSAPI OPR PATTERN File:

10.887.00

VSAPI OPR PATTERN Date:

26 Jun 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

Restart in Safe Mode

[ Learn More ]

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • x7 = "{malware path and file name}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Hardware Profiles\Current\System\CurrentControlSet\Enum\PCI\VEN_{value1}&DEV_{value2}&SUBSYS_{value3}&REV_{value4}\{value}
    • CSConfigFlags = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\PCI\VEN_{value1}&DEV_{value2}&SUBSYS_{value3}&REV_{value4}\{value}\Control
    • DisableCount = "0"

Step 4

Restore this deleted registry key/value from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\PCI\VEN_{value1}&DEV_{value2}&SUBSYS_{value3}&REV_{value4}\{value}\LogConf
BootConfig = {hex values}

Step 5

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

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_ZEGOST.YN. 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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