BKDR_NFLOG.AGZ

October 09, 2012
 Analysis by: Abraham Latimer Camba
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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 may be downloaded by other malware/grayware from remote sites.

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

  TECHNICAL DETAILS

File Size:

67,072 bytes

File Type:

OCX

Memory Resident:

Yes

Initial Samples Received Date:

28 Aug 2012

Payload:

Connects to URLs/IPs

Arrival Details

This backdoor may be downloaded by the following malware/grayware from remote sites:

  • TROJ_NFLOG.AGZ

It may be downloaded from the following remote sites:

  • http://www.{BLOCKED}ab.com/NfLog/Nfile.asp

Other System Modifications

This backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Clock
HID = "{hex values}"

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://www.{BLOCKED}ab.com/NfLog/NfCommand.asp
  • http://www.{BLOCKED}ab.com/NfLog/NfFile.asp
  • http://www.{BLOCKED}ab.com/NfLog/NfHostInfo.asp
  • http://www.{BLOCKED}ab.com/NfLog/NfStart.asp
  • http://www.{BLOCKED}ab.com/NfLog/NfUpda.asp
  • http://www.{BLOCKED}ab.com/NfLog/Nfpredown.asp
  • http://www.{BLOCKED}ab.com/NfLog/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

Stolen Information

This backdoor saves the stolen information in the following file:

  • %Temp%\$NtUninstallKB942388$

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

NOTES:

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

  • http://www.{BLOCKED}ab.com/NfLog/NfStart.asp

  SOLUTION

Minimum Scan Engine:

9.200

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 the malware/grayware file that dropped/downloaded BKDR_NFLOG.AGZ

Step 3

Restart in Safe Mode

[ Learn More ]

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\Clock
    • HID = "{hex values}"

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_NFLOG.AGZ. 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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