Analysis by: Alvin Bacani
 Modified by: Jimelle Monteser

ALIASES:

Backdoor.Win32.Hackdoor.gm (Kaspersky)

 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: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This backdoor arrives as a file that exports the functions of other malware/grayware. It arrives as a component bundled with malware/grayware packages.

It does not have any propagation routine.

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

It requires its main component to successfully perform its intended routine.

  TECHNICAL DETAILS

File Size: 200,704 bytes
File Type: DLL
Initial Samples Received Date: 26 Jul 2013

Arrival Details

This backdoor arrives as a file that exports the functions of other malware/grayware.

It arrives as a component bundled with malware/grayware packages.

Installation

This backdoor drops the following file(s)/component(s):

  • %System%\drivers\dump_En.sys - deleted afterwards
  • %System%\drivers\dump_.sys - deleted afterwards

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\SystemTime0
  • Global\SystemTime2

Autostart Technique

This backdoor starts the following services:

  • IPFILTERDRIVER
  • dump_

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER\
0000

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER\
0000\Control

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IpFilterDriver\Enum

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IpFilterDriver

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\dump_

It adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER
NextInstance = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER\
0000
Service = "IpFilterDriver"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER\
0000
Legacy = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER\
0000
ConfigFlags = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER\
0000
Class = "LegacyDriver"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER\
0000
ClassGUID = {GUID}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER\
0000\Control
NewlyCreated* = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_IPFILTERDRIVER\
0000\Control
ActiveService = "IpFilterDriver"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\dump_
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\dump_
Start = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\dump_
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\dump_
DisplayName = "dump_"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IpFilterDriver\Enum
0 = "Root\LEGACY_IPFILTERDRIVER\0000"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IpFilterDriver\Enum
Count = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IpFilterDriver\Enum
NextInstance = "1"

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

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

  • Manage Files (Search, Execute, Delete, Copy, Move)
  • Manage Registries (Search, Delete, Create)
  • Manage Processes (Open, Terminate)
  • Manage Services (Query, Start)
  • Manage Windows
  • Manage Directories
  • Shut Down Computer
  • Download Files

Download Routine

This backdoor downloads a possibly malicious file from a certain URL. The URL where this malware downloads the said file depends on the parameter passed on to it by its components.

Information Theft

This backdoor gathers the following data:

  • OS Version
  • Host Name
  • Computer Name
  • IP Address

Other Details

This backdoor requires its main component to successfully perform its intended routine.

NOTES:

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.178.07
FIRST VSAPI PATTERN DATE: 26 Jul 2013
VSAPI OPR PATTERN File: 10.179.00
VSAPI OPR PATTERN Date: 27 Jul 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

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\Enum\Root
    • LEGACY_IPFILTERDRIVER
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\IpFilterDriver<
    • Enum
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • dump_

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR_HACKDOOR.BB. 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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