Analysis by: Cris Nowell Pantanilla
 Modified by: Christopher Daniel So
ALIASES:

TrojanSpy:Win32/Derusbi.A (Microsoft)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This spyware 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: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 12 Aug 2011

Arrival Details

This spyware 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 spyware drops the following files:

  • %System%\msusb{random 3 characters}.dat - also detected by Trend Micro as TSPY_DERUSBI.A

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It drops the following component file(s):

  • %System%\drivers\{bc87739c-6024-412c-b489-b951c2f17000}.sys - detected by Trend Micro as TSPY_DERUSBI.E

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Autostart Technique

This spyware modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv\Parameters
ServiceDll = "%Systemroot%\System32\msusb{random 3 characters}.dat"

(Note: The default value data of the said registry entry is %System%\wuauserv.dll.)

Other System Modifications

This spyware adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\PnP
Security = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv\Parameters
Security = "{random values}"

Other Details

This spyware connects to the following possibly malicious URL:

  • {BLOCKED}ree.{BLOCKED}1223.com
  • {BLOCKED}4.{BLOCKED}.111.30

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.350.03
FIRST VSAPI PATTERN DATE: 12 Aug 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by TSPY_DERUSBI.A

Step 3

Scan your computer with your Trend Micro product and note files detected as TSPY_DERUSBI.A

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Search and delete the file detected as TSPY_DERUSBI.A

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 6

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\CurrentControlSet\Control\PnP
    • Security = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wuauserv\Parameters
    • Security = "{random values}"

Step 7

Restore this modified 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\CurrentControlSet\Services\wuauserv\Parameters
    • From: ServiceDll = "%Systemroot%\System32\msusb{random 3 characters}.dat"
      To: ServiceDll = "%System%\wuauserv.dll"

Step 8

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