BKDR_NFLOG.SM

 Analysis by: Nikko Tamana

 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:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • 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.

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

  TECHNICAL DETAILS

File Size:

67,584 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

20 Dec 2012

Payload:

Compromises system security, Downloads files, Connects to URLs/IPs, Collects system information

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 file(s)/component(s):

  • %Temp%\YahooCache.ini
  • %Temp%\$NtUninstallKB942388$ - Contains stolen information

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

It injects itself into the following processes as part of its memory residency routine:

  • svchost.exe

Autostart Technique

This backdoor 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\IPRIP
Type = "20"

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

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IPRIP
ImagePath = "%SystemRoot%\System32\svchost.exe -k netsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IPRIP
DisplayName = "IPv6 Stack Local Support"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IPRIP
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IPRIP
Description = "Net address translation for IPv6 Protocol."

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IPRIP\Security
Security = "{hex values}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IPRIP\Parameters
ServiceDll = %Temp%\NfIpv6.ocx

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IPRIP

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IPRIP\Parameters

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IPRIP\Security

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings\P3P

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings\P3P\History

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\Cache\Extensible Cache\
MSHist01{Current date and the date the day after}

It adds the following registry entries:

HKEY_USERS\.DEFAULT\Software\
Microsoft\Clock
HID = "{hex values}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
WebView\BarricadedFolders
shell:Windows = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\Cache\Extensible Cache\
MSHist01{Current date and the date the day after}
CachePath = "%USERPROFILE%\Local Settings\History\History.IE5\MSHist01{Current date and the date the day after}\"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\Cache\Extensible Cache\
MSHist01{Current date and the date the day after}
CachePrefix = ":{Current date and the date the day after}: "

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\Cache\Extensible Cache\
MSHist01{Current date and the date the day after}
CacheLimit = "2000"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\Cache\Extensible Cache\
MSHist01{Current date and the date the day after}
CacheOptions = "b"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\Cache\Extensible Cache\
MSHist01{Current date and the date the day after}
CacheRepair = "0"

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings\Connections
DefaultConnectionSettings = "{Hex Values}"

It deletes the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\Cache\Extensible Cache\
MSHist01{Default}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\Cache\Extensible Cache\
MSHist012012110920121110

Backdoor Routine

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

  • Download files
  • Perform remote shell
  • Retrieve system information
  • Update self

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

  • http://{BLOCKED}t194.{BLOCKED}n.com/norton/NfCommand.asp
  • http://{BLOCKED}t194.{BLOCKED}n.com/norton/NfHostInfo.as
  • http://{BLOCKED}t194.{BLOCKED}n.com/norton/Nfile.asp
  • http://{BLOCKED}t194.{BLOCKED}n.com/norton/Nfpredown.asp
  • http://{BLOCKED}t194.{BLOCKED}n.com/norton/NfStart.asp
  • http://{BLOCKED}t194.{BLOCKED}n.com/norton/TTip.asp

It posts the following information to its command and control (C&C) server:

  • IP configuration
  • Network statistics
  • Running processes
  • Running services
  • System information

Download Routine

This backdoor accesses the following websites to download files:

  • http://{BLOCKED}t194.{BLOCKED}n.com/norton/Nfile.asp

It saves the files it downloads using the following names:

  • %Temp%\MSMAPI.OCX - Detected as BKDR_NFLOG.SM

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

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

Other Details

This backdoor requires the existence of the following files to properly run:

  • %Temp%\YahooCache.ini

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

NOTES:
This backdoor reports system infection by sending IP address and infection time to the following URL via HTTP post:

  • http://{BLOCKED}t194.{BLOCKED}n.com/norton/NfStart.asp

  SOLUTION

Minimum Scan Engine:

9.300

VSAPI OPR PATTERN File:

9.607.00

VSAPI OPR PATTERN Date:

20 Dec 2012

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 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\Services
    • IPRIP
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • P3P
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\Cache\Extensible Cache
    • MSHist01{Current date and the date the day after}

Step 4

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\WebView\BarricadedFolders
    • shell:Windows = "0"
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Clock
    • HID = "{hex values}"
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections
    • DefaultConnectionSettings = "{Hex Values}"

Step 5

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.
  • %Temp%\YahooCache.ini
  • %Temp%\$NtUninstallKB942388$ - Contains stolen information

Step 6

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

NOTES:
There is no need to restore the deleted registry keys.


Did this description help? Tell us how we did.