Virus

W32/Opaserv.C

Analysis

  • Virus is 32bit, with a size of 28,672 bytes and is a minor variant to W32/Opaserv.A – the only difference is in a couple of lines of code
  • Virus icon is that of a standard 32bit executable
  • Virus attempts to connect to opasoft.com and update itself however the hard-coded URL is no longer available\
  • Virus copies itself to the Windows folder as ScrSvr.exe and modifies the registry to load at Windows startup –

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
    CurrentVersion\Run
    ScrSvr = Windows\ScrSvr.exe

  • The virus will attempt to use SMB through NetBIOS seeking machines on the same IP subnet

  • The virus will scan IP addresses within the same domain for other shares, using NetBIOS via TCP port 137, seeking systems with open shares

  • If a system is found with an open share, the virus will copy itself to that machine in the Windows folder as ScrSvr.exe

  • The virus will modify the WIN.INI configuration file to load the dropped virus at Windows startup