Analysis by: Clive Fuentebella
ALIASES:

DDoS:Win32/Nitol.K (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware, Propagates via IRC, Propagates via network shares

This Worm 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 connects to a website to send and receive information.

It terminates itself if it detects it is being run in a virtual environment. It takes advantage of certain vulnerabilities. It requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.

  TECHNICAL DETAILS

File Size: 50,703 bytes
File Type: EXE
Memory Resident: Yes
Payload: Drops files, Connects to URLs/IPs

Arrival Details

This Worm 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 Worm drops the following copies of itself into the affected system and executes them:

  • %System%\smsc.exe
  • {Removable drive}\RECYCLER\{SID}\update.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It drops the following files:

  • %System Root%\sdfeww.bat (batch file for manipulating registries)
  • %User Temp%\7684d.reg
  • {Removable drive}\RECYCLER\{SID}\Desktop.ini
  • {Removable drive}\autorun.inf

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • cmd /c net stop SharedAccess
  • %System Root%\sdfeww.bat
  • cmd /c net stop "Security Center"
  • cmd /c net start SharedAccess

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • dfgregrethgsnghjdg434grthgwer443we123

Autostart Technique

This Worm starts the following services:

  • Service name: PrtSmanm
    Image path: %System%\smsc.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Other System Modifications

This Worm adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International
W2KLpk = 0

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Shell Extensions
systemdates = {Malware file path and name}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Shell Extensions
{Malware file name} = {Malware filename}:*:Enabled:Microsoft Enabled

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control
WaitToKillServiceTimeout = 7000

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\Tcpip\Parameters
MaxFreeTcbs = 2000

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\Tcpip\Parameters
MaxHashTableSize = 2048

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\Tcpip\Parameters
MaxUserPort = 63000

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\Tcpip\Parameters
TcpTimedWaitDelay = 30

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\SharedAccess
Start = 2 (Default: 3)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
EnableFirewall = 0 (Default: 1)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\wscsvc
Start = 4 (Default: 2)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\wuauserv
Start = 4 (Default: 2)

Backdoor Routine

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

  • Downloads and executes files
  • Updates itself
  • Executes arbitrary commands
  • Propagates via IRC
  • Propagates via network via brute-forcing
  • Performs network flood attacks (e.g. TCP, UDP, ICMP, HTTP GET)
  • Adds/deletes users in the network
  • Starts SOCKS4 server

It connects to the following websites to send and receive information:

  • {BLOCKED}.165.98.198
  • {BLOCKED}.strangled.net
  • {BLOCKED}arc.isthebe.st
  • {BLOCKED}.chickenkiller.com
  • {BLOCKED}rcc.ignorelist.com
  • {BLOCKED}fc.assexyas.com
  • {BLOCKED}reak.uglyas.com
  • {BLOCKED}ost.crabdance.com
  • {BLOCKED}ngag.jumpingcrab.com
  • {BLOCKED}hh.twilightparadox.com
  • {BLOCKED}ost.mooo.com

Information Theft

Upon execution of the affected application, it gathers the following information:

  • OS information (e.g. version, name)
  • IP address

Other Details

This Worm connects to the following URL(s) to get the affected system's IP address:

  • http://download.{BLOCKED}.com
  • http://check.{BLOCKED}.eu
  • http://itip1.{BLOCKED}e.com
  • http://www.{BLOCKED}.com/ips8.asp
  • http://checkip.{BLOCKED}.com
  • http://checkip.{BLOCKED}.com

It terminates itself if it detects it is being run in a virtual environment.

It does the following:

  • It may enable or disable remote desktop connections through manipulating the following registry entry:
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\fDenyTSConnections
  • It may change the port number of remote desktop connections through maniplating the following registry entry:
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\Wds\rdpwd\Tds\tcp\PortNumber
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp\PortNumber

It takes advantage of the following vulnerabilities:

  • MS06-040 - Vulnerability in Server Service Could Allow Remote Code Execution

It does not proceed to its malicious routine if it detects that it is being debugged.

It requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.846.04
FIRST VSAPI PATTERN DATE: 16 Jul 2021
VSAPI OPR PATTERN File: 16.847.00
VSAPI OPR PATTERN Date: 17 Jul 2021

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

Disable this malware service

[ Learn More ]
  • PrtSmanm

Step 5

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\Internet Explorer\International
    • W2KLpk=0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Shell Extensions
    • systemdates={Malware file path and name}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Shell Extensions
    • {Malware file name}={Malware filename}:*:Enabled:Microsoft Enabled
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control
    • WaitToKillServiceTimeout=7000
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\Tcpip\Parameters
    • MaxFreeTcbs=2000
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\Tcpip\Parameters
    • MaxHashTableSize=2048
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\Tcpip\Parameters
    • MaxUserPort=63000
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\Tcpip\Parameters
    • TcpTimedWaitDelay=30

Step 6

Restore this modified 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\SYSTEM\ControlSet001\services\SharedAccess
    • Start=2
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
    • EnableFirewall=0
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\wscsvc
    • Start=4
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\wuauserv
    • Start=4

Step 7

Search and delete these files

[ 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.
  • %System Root%\sdfeww.bat (batch file for manipulating registries)
  • %User Temp%\7684d.reg
  • {Removable drive}\RECYCLER\{SID}\Desktop.ini
  • {Removable drive}\autorun.inf
  • %System%\smsc.exe
  • {Removable drive}\RECYCLER\{SID}\update.exe

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.KOLAB.QNLU. 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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