Analysis by: Christopher Daniel So
ALIASES:

Trojan:Win32/Reder.A (Microsoft), Trojan.Neloweg (Symantec), Trojan-Banker.Win32.Neloweg.a (Kaspersky)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003, Windows Vista, Windows 7

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This malware is the dropper for the malware BKDR_NELOWEG.DD, a backdoor whose primary purpose is stealing information from online transactions, which is capable of running on Windows Vista and Windows 7.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan 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: EXE
Memory Resident: No
Initial Samples Received Date: 01 Mar 2012
Payload: Drops files

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\UDP

It adds the following registry entries:

HKEY_CURRENT_USER\UDP
v = "{malware version}"

HKEY_CURRENT_USER\UDP
g = "{obfuscated C&C server URL}"

HKEY_CURRENT_USER\UDP
!alt! = "{obfuscated alternate C&C server URLs}"

HKEY_CURRENT_USER\UDP
id = "{random installation GUID}"

HKEY_CURRENT_USER\UDP
i = "{encrypted system information}"

Dropping Routine

This Trojan drops the following files:

  • %System%\{random file name}.dll - detected by Trend Micro as BKDR_NELOWEG.DD

(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.)

NOTES:

It installs the dropped file %System%\{random file name}.dll as a namespace provider. Doing so would load the DLL each time the Winsock library is loaded. As a consequence, the following registry key is created:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
WinSock2\Parameters\NameSpace_Catalog5\Catalog_Entries\000000000004

The following registry entries are also added:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
WinSock2\Parameters\NameSpace_Catalog5\Catalog_Entries\000000000004
LibraryPath = "%System%\tve32.dll"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
WinSock2\Parameters\NameSpace_Catalog5\Catalog_Entries\000000000004
DisplayString = "UDP"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
WinSock2\Parameters\NameSpace_Catalog5\Catalog_Entries\000000000004
ProviderId = "{binary GUID}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
WinSock2\Parameters\NameSpace_Catalog5\Catalog_Entries\000000000004
SupportedNameSpace = "0c"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
WinSock2\Parameters\NameSpace_Catalog5\Catalog_Entries\000000000004
Enabled = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
WinSock2\Parameters\NameSpace_Catalog5\Catalog_Entries\000000000004
Version = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
WinSock2\Parameters\NameSpace_Catalog5\Catalog_Entries\000000000004
StoresServiceClassInfo = "0"

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.808.08
FIRST VSAPI PATTERN DATE: 01 Mar 2012
VSAPI OPR PATTERN File: 8.809.00
VSAPI OPR PATTERN Date: 01 Mar 2012

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 TROJ_NELOWEG.DD

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_CURRENT_USER
    • UDP
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\Parameters\NameSpace_Catalog5\Catalog_Entries
    • 000000000004

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_NELOWEG.DD. 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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