Lovesan is an Internet Worm which exploits the DCOM RPC vulnerability in Microsoft Windows described in MS Security Bulletin MS03-026.
Lovesan is written in C using the LCC compiler. The worm is a Windows PE EXE file about 6KB (compressed via UPX – 11KB when decompressed).
Lovesan downloads and attempts to run a file named msblast.exe.
The text is as follows:
Symptoms of Infection:
How the Worm Spreads
Lovesan registers itself in the autorun key when the system reboots and launches itself every time the computer reboots in the future:
HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun windows auto update="msblast.exe"
The worm then scans IP addresses, attempting to connect to 20 random IP addresses and infect any vulnerable machines. Lovesan sleeps for 1.8 seconds and scans the next 20 IP addresses.
Lovesan scans IP addresses following one of the patterns below:
The worm sends a buffer-overrun request to vulnerable machines via TCP port 135. The newly infected machine then initiates the command shell on TCP port 4444.
Lovesan runs the thread that opens the connection on port 4444 and waits for FTP ‘get’ request from the victim machine. The worm then forces the victim machine to sends the ‘FTP get’ request. Thus the victim machine downloads the worm from the infected machine and runs it. The victim machine is now also infected.
Once a computer is infected the system sends an error message about RPC service failure and may reboot the machine.
As of August 16, 2003 Lovesan will launch DDoS attacks on the Windowsupdate.com server.