BKDR_ZEGOST.AWT

April 11, 2014
 ALIASES:

Backdoor:Win32/Zegost.Q (Microsoft); Backdoor.Trojan (Symantec); Trojan.Win32.Jorik.Zegost.qis (Kaspersky); Backdoor.Win32.Zegost.q (v) (Sunbelt); Trojan horse BackDoor.Generic16.AESI (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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:

28,925,952 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Apr 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:

  • %Program Files%\Common Files\Sogou.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

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
hao567 = "%Program Files%\Common Files\Sogou.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\MediaResources\msvideo

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\BITS
InitTime = "20140404"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\BITS
Version = "Ball"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\BITS
Group = "ĬÈÏ·Ö×é"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Devices Manager
Description = "¼à²âºÍ¼àÊÓÐÂÓ²¼þÉ豸²¢ÇÒ×Ô¶¯¸üÐÂÉ豸Çý¶¯¡£"

Dropping Routine

This backdoor drops the following files:

  • %System%\Sougou.exe
  • %User Profile%\Startup\hao567.exe
  • %Program Files%\Common Files\Sogou.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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\Control\MediaResources
    • msvideo

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\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • hao567 = "%Program Files%\Common Files\Sogou.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\BITS
    • InitTime = "20140404"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\BITS
    • Version = "Ball"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\BITS
    • Group = "ĬÈÏ·Ö×é"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Devices Manager
    • Description = "¼à²âºÍ¼àÊÓÐÂÓ²¼þÉ豸²¢ÇÒ×Ô¶¯¸üÐÂÉ豸Çý¶¯¡£"

Step 5

Search and delete these components

[ Learn More ]
There may be some components 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%\Sougou.exe
  • %User Profile%\Startup\hao567.exe
  • %Program Files%\Common Files\Sogou.exe

Step 6

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