BKDR_AGENT.FZW


 ALIASES:

Adware:Win32/Kraddare (Microsoft); Generic BackDoor!1t3 (McAfee); SecurityRisk.Dropper, SecurityRisk.Downldr (Symantec); ARC:NSIS, [qtldquqo.dll]:Backdoor.Win32.Agent.cizl (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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 deletes itself after execution.

  TECHNICAL DETAILS

File Size:

127,307 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

17 Jul 2012

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 creates the following folders:

  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\ADMINI~1
  • %User Profile%\LOCALS~1
  • %User Temp%\nsm3.tmp
  • %Program Files%\qtldquqo

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %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.. %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).)

Other System Modifications

This backdoor deletes the following files:

  • %User Temp%\nsm1.tmp
  • %User Temp%\nsm3.tmp

(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 adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\qtldquqo

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\qtldquqo\Parameters

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\qtldquqo
ver = "20120523"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\qtldquqo\Parameters
ServiceDll = "%Program Files%\qtldquqo\qtldquqo.dll"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
netsvcs = "{random characters}"

(Note: The default value data of the said registry entry is {random values}.)

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\nsm2.tmp
  • %User Temp%\nsm3.tmp\System.dll
  • %User Temp%\nsm3.tmp\Math.dll
  • %User Temp%\nsm3.tmp\InstallAssist.dll
  • %Program Files%\qtldquqo\qtldquqo.dll

(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.. %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).)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://www.{BLOCKED}num.comcounter/mac_proc.php?{random characters}
  • http://www.{BLOCKED}num.comcheck_counter.php?{random characters}

It deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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

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\SOFTWARE
    • qtldquqo
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\qtldquqo
    • Parameters

Step 3

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\SOFTWARE\qtldquqo
    • ver = "20120523"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\qtldquqo\Parameters
    • ServiceDll = "%Program Files%\qtldquqo\qtldquqo.dll"

Step 4

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • From: netsvcs = "{random characters}"
      To: netsvcs = ""{random values}""

Step 5

Search and delete these components

[ Learn More ]
There may be some components 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%\nsm2.tmp
  • %User Temp%\nsm3.tmp\System.dll
  • %User Temp%\nsm3.tmp\Math.dll
  • %User Temp%\nsm3.tmp\InstallAssist.dll
  • %Program Files%\qtldquqo\qtldquqo.dll

Step 6

Search and delete these folders

[ 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.
  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\ADMINI~1
  • %User Profile%\LOCALS~1
  • %User Temp%\nsm3.tmp
  • %Program Files%\qtldquqo

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_AGENT.FZW. 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.

Step 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Temp%\nsm1.tmp
  • %User Temp%\nsm3.tmp


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