W32/Randex.B

Analysis

• Virus is 32bit, with a UPX compressed size of 32,256 bytes
  
• Virus bears resemblance to W32/Randex.c in spread method and mechanism
  
• If virus is run, it creates a Mutex named “msejaer32” and runs memory resident
  
• The virus may run in as many as 40 threads simultaneously and attempts to connect in rapid succession to numerous and random IP addresses across the Internet in an effort to locate open shares and copy itself to that potential target as the file “msmsgri.exe”
  
• Virus uses the import “WNetAddConnection2A” from MPR.DLL in order to connect with the target, and uses the import “NetScheduleJobAdd” from “NETAPI32.DLL in order to initiate running the virus on the remote host
  
• If viable targets are located, virus will attempt to copy itself to the c$\System32 or Admin$\System32 share as “msmsgri.exe” then issue a remote instruction to run the file
  
• Virus may attempt to connect simultaneously to as many as 20 different IP addresses
  
• Virus deletes keys in the registry which store IP address configuration data –

  HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\
  {machine specific CSLID value}\Parameters\Tcpip\
  "DhcpDefaultGateway"
  "DhcpSubnetMaskOpt"

  HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\
  Dhcp\Parameters\
  "{machine specific CSLID value}"

  HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\NetBT\
  Parameters\Interfaces\Tcpip_{machine specific CSLID value}\
  "DhcpNameServerList"

  HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\
  Tcpip\Parameters\
  "DhcpDomain"
  "DhcpNameServer"

  HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\
  Parameters\Interfaces\{machine specific CSLID value}\
  "DhcpDefaultGateway"
  "DhcpDomain"
  "DhcpNameServer"
  "DhcpSubnetMaskOpt"

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
  {machine specific CSLID value}\Parameters\Tcpip\
  "DhcpDefaultGateway"
  "DhcpSubnetMaskOpt"

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
  Dhcp\Parameters\
  "{machine specific CSLID value}"

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetBT\
  Parameters\Interfaces\Tcpip_{machine specific CSLID value}\
  "DhcpNameServerList"

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
  Tcpip\Parameters\
  "DhcpDomain"
  "DhcpNameServer"

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\
  Parameters\Interfaces\{machine specific CSLID value}
  "DhcpDefaultGateway"
  "DhcpDomain"
  "DhcpNameServer"
  "DhcpSubnetMaskOpt"
  

• Virus changes keys in the registry which store IP address configuration data –

  HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\
  {machine specific CSLID value}\Parameters\Tcpip\
  "DhcpIPAddress" = 169.254.214.144
  "DhcpServer" = 255.255.255.255
  "DhcpSubnetMask" = 255.255.0.0
  "Lease" = 00, 00, 00, 00

  HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\
  Parameters\Interfaces\{machine specific CSLID value}\
  "DhcpIPAddress" = 169.254.214.144
  "DhcpServer" = 255.255.255.255
  "DhcpSubnetMask" = 255.255.0.0
  "IPAutoconfigurationAddress" = 169.254.214.144
  "Lease" = 00, 00, 00, 00

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
  {machine specific CSLID value}\Parameters\Tcpip\
  "DhcpIPAddress" = 169.254.214.144
  "DhcpServer" = 255.255.255.255
  "DhcpSubnetMask" = 255.255.0.0

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\
  Parameters\Interfaces\{machine specific CSLID value}
  "DhcpIPAddress" = 169.254.214.144
  "DhcpServer" = 255.255.255.255
  "DhcpSubnetMask" = 255.255.0.0
  "IPAutoconfigurationAddress" = 169.254.214.144
  

• Virus may add an entry into the system registry in order to load at Windows startup –

  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
  CurrentVersion\Run\
  "mssyslanhelper" = C:\Windows\System32\msmsgri.exe
  

• Virus attempts to connect to the IP address 217.21.117.104 using TCP port 54545 – this connection appears to be in Rhode Island, U.S.