Worm.VBS.PSYME.A

 Analysis by: Mohammed Malubay

 ALIASES:

Trojan.VBS.Agent.dg(KASPERSKY); VBS/Psyme.b(NAI); W32.SillyFDC(NORTON);

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

3,261 bytes

File Type:

VBS

Initial Samples Received Date:

28 Feb 2020

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:

  • %Application Data%\Microsoft\Windows\Templates\{malware filename}.vbs

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

It drops the following files:

  • {drive letter}:\autorun.inf
  • %Application Data%\Microsoft\Windows\Templates\1.exe
  • %Application Data%\Microsoft\Windows\Templates\2.exe
  • %Application Data%\Microsoft\Windows\Templates\3.exe
  • %Application Data%\Microsoft\Windows\Templates\4.exe
  • %Application Data%\Microsoft\Windows\Templates\5.exe
  • %Application Data%\Microsoft\Windows\Templates\6.exe
  • %Application Data%\Microsoft\Windows\Templates\7.exe
  • %Application Data%\Microsoft\Windows\Templates\8.exe
  • %Application Data%\Microsoft\Windows\Templates\9.exe
  • %Application Data%\Microsoft\Windows\Templates\10.exe

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

It adds the following processes:

  • "%System%\attrib.exe" +a +s +h +r "%Application Data%\Microsoft\Windows\Templates\{malware filename}.vbs"
  • "%System%\attrib.exe" +a +s +h +r "C:\autorun.inf"
  • "%System%\attrib.exe" +a +s +h +r "C:\{malware filename}.vbs"
  • "%System%\attrib.exe" +a +s +h +r "D:\autorun.inf"
  • "%System%\attrib.exe" +a +s +h +r "D:\{malware filename}.vbs"
  • "%System%\attrib.exe" +a +s +h +r "F:\autorun.inf"
  • "%System%\attrib.exe" +a +s +h +r "F:\{malware filename}.vbs"
  • "%System%\attrib.exe" +a +s +h +r "G:\autorun.inf"
  • "%System%\attrib.exe" +a +s +h +r "G:\{malware filename}.vbs"
  • "%System%\attrib.exe" -a -s -h -r "C:\autorun.inf"
  • "%System%\attrib.exe" -a -s -h -r "D:\autorun.inf"
  • "%System%\attrib.exe" -a -s -h -r "F:\autorun.inf"
  • "%System%\attrib.exe" -a -s -h -r "G:\autorun.inf"
  • "%System%\taskkill.exe" /im 360tray.exe
  • "%System%\WScript.exe" "%Desktop%\{malware filename}.vbs"
  • "%Windows%\system32\ntvdm.exe" -i1
  • "%Windows%\system32\ntvdm.exe" -i2
  • "%Windows%\system32\ntvdm.exe" -i3
  • "%Windows%\system32\ntvdm.exe" -i4
  • "%Windows%\system32\ntvdm.exe" -i5
  • "%Windows%\system32\ntvdm.exe" -i6
  • "%Windows%\system32\ntvdm.exe" -i7
  • "%Windows%\system32\ntvdm.exe" -i8
  • "%Windows%\system32\ntvdm.exe" -i9
  • "%Windows%\system32\ntvdm.exe" -ia

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

Other System Modifications

This Worm adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
system = wscript.exe "%Application Data%\Microsoft\Windows\Templates\{malware filename}.vbs" t

HKEY_LOCAL_MACHINE\SOFTWARE\MSGNLMSL
start = 351

Propagation

This Worm drops the following copies of itself in all physical and removable drives:

  • {drive letter}:\{malware filename}.vbs

Other Details

This Worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\MSGNLMSL

It connects to the following possibly malicious URL:

  • http://{BLOCKED}l.sh.com/1.exe
  • http://{BLOCKED}l.sh.com/2.exe
  • http://{BLOCKED}l.sh.com/3.exe
  • http://{BLOCKED}l.sh.com/4.exe
  • http://{BLOCKED}l.sh.com/5.exe
  • http://{BLOCKED}l.sh.com/6.exe
  • http://{BLOCKED}l.sh.com/7.exe
  • http://{BLOCKED}l.sh.com/8.exe
  • http://{BLOCKED}l.sh.com/9.exe
  • http://{BLOCKED}l.sh.com/10.exe

However, as of this writing, the said sites are inaccessible.