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BKDR_GBOT.C

October 03, 2013
 Analysis by: Maydalene Edsel Salvador
 Modified by: Rika Joi Gregorio
 ALIASES:

Trojan:Win32/Comrerop (Microsoft), Trojan.Gen (Norton), Mal/DelpDldr-B (Sophos), Trojan.Win32.Generic!BT (Sunbelt), W32/DelpDldr.B!tr (Fortinet)

 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: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet


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 executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

40,960 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Apr 2013

Payload:

Connects to URLs/IPs

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:

  • %Windows%\nightupdate\svchost.exe

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

It creates the following folders:

  • %Windows%\nightupdate

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

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\policies\
Explorer\Run
UpdateSvchost = "%Windows%\nightupdate\svchost.exe"

Other System Modifications

This backdoor creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\AuthorizedApplications\List
UpdateSvchost = "%Windows%\nightupdate\svchost.exe:*:Enabled:svchost"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • httpflood - HTTP flooding
  • ahttpflood - Asynchronous HTTP flooding
  • simplehttpflood - HTTP flooding in simple mode
  • posthttpflood - HTTP flooding (POST)
  • ontcpflood - TCP flooding
  • icmpflood - ICMP flooding
  • stop - cancel previous command
  • update - update itself

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}em.in/only/getcmd.php?id=-{Malware ID}&traff=0

NOTES:

It uses the following websites as its fake referrer:

  • http: /kvk-business.com/sozdanie-saytov/
  • http://er.ru/
  • http://fc-zenit.ru/
  • http://kremlin.ru/
  • http://mvd.ru/
  • http://pella.ru/
  • http://premier.gov.ru/
  • http://pvppw.ru/
  • http://vkontakte.ru/
  • http://www.gofuckbiz.com/
  • http://www.niagarastar.ru/
  • http://www.odnoklassniki.ru/
  • http://www.pfc-cska.com/splash/
  • http://www.rfs.ru/
  • http://zhyk.ru/

  SOLUTION

Minimum Scan Engine:

9.300

VSAPI OPR PATTERN File:

9.872.05

VSAPI OPR PATTERN Date:

22 Apr 2013

OPP PATTERN File:

9.873.00

OPP PATTERN Date:

22 Apr 2013

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\policies\Explorer\Run
    • UpdateSvchost = "%Windows%\nightupdate\svchost.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\AuthorizedApplications\List
    • UpdateSvchost = "%Windows%\nightupdate\svchost.exe:*:Enabled:svchost"

Step 4

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Windows%\nightupdate

Step 5

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