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TROJ_CARBERP.YUG

August 26, 2014
 Analysis by: Vincent Martin Hermosura
 ALIASES:

TrojanDownloader:Win32/Carberp (Microsoft), Downloader (Symmantec), [3.nsis]:Generic-FAUV!D0E31502E60F (Mcafee), Trojan.Win32.Generic!BT (Sunbelt), TR/Crypt.XPACK.Gen8 (Antivir), W32/Trojan5.KJU (Authentium), Trojan-Spy.Win32.Zbot, Trojan-Spy.Win32.Zbot (Ikarus), a variant of Win32/Injector.BJOJ trojan, a variant of Win32/Injector.BJOJ trojan (Esset), Backdoor.Hlux (Vba32)

 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: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 Jul 2014

Payload:

Downloads 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.

Installation

This Trojan adds the following folders:

  • %Program Files%\NVIDIA Corporation
  • %Program Files%\NVIDIA Corporation\Update Center
  • %User Temp%\{random}.tmp

(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).. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It drops the following copies of itself into the affected system:

  • %Program Files%\NVIDIA Corporation\Update Center\nvdupdate.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).)

It drops the following non-malicious file:

  • %User Temp%\{random}.tmp\System.dll - deleted afterwards

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv
Type = "10"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv
ImagePath = "%Program Files%\NVIDIA Corporation\Update Center\nvdupdate.exe /svc"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv
DisplayName = "NVIDIA Update Server"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv
"LocalSystem" = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv
Description = "NVIDIA Settings Update Manager service, used to check new updates from NVIDIA server"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv\Security
Security = "{hex value}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv\Enum
0 = "Root\LEGACY_NVUPDSRV\0000"

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

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

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv\Security

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NvUpdSrv\Enum

Other System Modifications

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

HKEY_CURRENT_USER\Software\NVIDIA Corporation\
Global\nvUpdSrv
value = "{year}{month}{day}"

HKEY_CURRENT_USER\Software\NVIDIA Corporation\
Global\nvUpdSrv
"{GUID}" = "{GUID}"

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

HKEY_CURRENT_USER\Software\!

HKEY_CURRENT_USER\Software\!\
GridTest

HKEY_CURRENT_USER\Software\!\
GridTest\Recent File List

HKEY_CURRENT_USER\Software\!\
GridTest\Settings

HKEY_CURRENT_USER\Software\NVIDIA Corporation

HKEY_CURRENT_USER\Software\NVIDIA Corporation\
Global

HKEY_CURRENT_USER\Software\NVIDIA Corporation\
Global\nvUpdSrv

Download Routine

This Trojan connects to the following URL(s) to download its component file(s):

  • {BLOCKED}.{BLOCKED}82.41
  • {BLOCKED}.{BLOCKED}.145.233
  • {BLOCKED}.{BLOCKED}.145.242
  • {BLOCKED}.{BLOCKED}.140.146
  • {BLOCKED}.{BLOCKED}.62.114
  • {BLOCKED}.{BLOCKED}.28.30
  • {BLOCKED}.{BLOCKED}.137.229
  • {BLOCKED}.{BLOCKED}.250.34
  • {BLOCKED}.{BLOCKED}.198.182
  • {BLOCKED}.{BLOCKED}.113.162
  • {BLOCKED}.{BLOCKED}.130.17
  • {BLOCKED}.{BLOCKED}.97.176
  • {BLOCKED}.{BLOCKED}.157.42
  • {BLOCKED}.{BLOCKED}.96.17
  • {BLOCKED}.{BLOCKED}.74.93
  • {BLOCKED}.{BLOCKED}.152.141
  • {BLOCKED}.{BLOCKED}.4.167
  • {BLOCKED}.{BLOCKED}.133.164
  • {BLOCKED}.{BLOCKED}.113.145
  • {BLOCKED}.{BLOCKED}.206.186
  • {BLOCKED}.{BLOCKED}.116.234
  • {BLOCKED}.{BLOCKED}.137.179
  • {BLOCKED}.{BLOCKED}.205.159
  • {BLOCKED}.{BLOCKED}.165.113
  • {BLOCKED}.{BLOCKED}.33.126
  • {BLOCKED}.{BLOCKED}.186.236
  • {BLOCKED}.{BLOCKED}.231.185
  • {BLOCKED}.{BLOCKED}.175.20
  • {BLOCKED}.{BLOCKED}.116.213
  • {BLOCKED}.{BLOCKED}.180.16
  • {BLOCKED}.{BLOCKED}.88.50
  • {BLOCKED}.{BLOCKED}.179.119
  • {BLOCKED}.{BLOCKED}.227.173
  • {BLOCKED}.{BLOCKED}.214.110
  • {BLOCKED}.{BLOCKED}.29.219
  • {BLOCKED}.{BLOCKED}.58.68
  • {BLOCKED}.{BLOCKED}.72.1
  • {BLOCKED}.{BLOCKED}.151.70
  • {BLOCKED}.{BLOCKED}.178.95
  • {BLOCKED}.{BLOCKED}.150.107
  • {BLOCKED}.{BLOCKED}.49.215
  • {BLOCKED}.{BLOCKED}.67.39
  • {BLOCKED}.{BLOCKED}.227.159
  • {BLOCKED}.{BLOCKED}.9.238
  • {BLOCKED}.{BLOCKED}.223.222
  • {BLOCKED}.{BLOCKED}.25.160
  • {BLOCKED}.{BLOCKED}.101.66
  • {BLOCKED}.{BLOCKED}.49.140
  • {BLOCKED}.{BLOCKED}.80.158
  • {BLOCKED}.{BLOCKED}.26.250
  • {BLOCKED}.{BLOCKED}.11.115
  • {BLOCKED}.{BLOCKED}.1.50
  • {BLOCKED}.{BLOCKED}.5.171
  • {BLOCKED}.{BLOCKED}.102.29
  • {BLOCKED}.{BLOCKED}.236.147
  • {BLOCKED}.{BLOCKED}.198.136
  • {BLOCKED}.{BLOCKED}.119.85
  • {BLOCKED}.{BLOCKED}.138.34

It saves the files it downloads using the following names:

  • %User Temp%\{random}.tmp.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

NOTES:

It downloads files by connecting to the IP address mentioned above and sending an HTTP GET request. It does this by appending the following strings:

  • /stat?uid={value}&downlink={value}&uplink={value}&id={value}&statpass={value}&version={value}&features={value}&guid={value}&comment={value}&p={value}&s={value}

  SOLUTION

Minimum Scan Engine:

9.700

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • NvUpdSrv
  • In HKEY_CURRENT_USER\Software
    • !
  • In HKEY_CURRENT_USER\Software\NVIDIA Corporation\Global
    • nvUpdSrv

Step 5

Search and delete this folder

[ 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.
  • %User Temp%\{random}.tmp

Step 6

Search and delete this file

[ Learn More ]
There may be some files 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.
  • %User Temp%\{random}.tmp.exe

Step 7

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