View Full Version : w32.blaster.e.worm *IMPORTANT XP USER*

29-08-03, 09:45
W32.Blaster.E.Worm is a worm that exploits the DCOM RPC vulnerability (described in Microsoft Security Bulletin MS03-026) using TCP port 135. The worm targets only Windows 2000 and Windows XP machines. While Windows NT and Windows 2003 Server machines are vulnerable to the aforementioned exploit (if not properly patched), the worm is not coded to replicate to those systems. This worm attempts to download the mslaugh.exe file to the %WinDir%\system32 directory and then execute it. W32.Blaster.E.Worm does not have a mass-mailing functionality.

Recommended that you block access to TCP port 4444 at the firewall level, and then block the following ports, if you do not use the following applications:

TCP Port 135, "DCOM RPC"
UDP Port 69, "TFTP"

The worm also attempts to perform a Denial of Service (DoS) on kimble.org. This is an attempt to prevent you from applying a patch on your computer against the DCOM RPC vulnerability.

When W32.Blaster.E.Worm is executed, it does the following:

Checks to see whether a computer is already infected and whether the worm is running. If so, the worm will not infect the computer a second time.

Adds the value:

"windows automation"="mslaugh.exe"

to the registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Curr entVersion\Run

so that the worm runs when you start Windows.

Generates an IP address and attempts to infect the computer that has that address. The IP address is generated according to the following algorithms:

For 40% of the time, the generated IP address is of the form A.B.C.0, where A and B are equal to the first two parts of the infected computer's IP address.

C is also calculated by the third part of the infected system's IP address; however, for 40% of the time the worm checks whether C is greater than 20. If so, a random value less than 20 is subtracted from C. Once the IP address is calculated, the worm will attempt to find and exploit a computer with the IP address A.B.C.0.

The worm will then increment the 0 part of the IP address by 1, attempting to find and exploit other computers based on the new IP address, until it reaches 254.

With a probability of 60%, the generated IP address is completely random.

Sends data on TCP port 135 that may exploit the DCOM RPC vulnerability. The worm sends one of two types of data: either to exploit Windows XP or Windows 2000.

For 80% of the time, Windows XP data will be sent; and for 20% of the time, the Windows 2000 data will be sent.

The local subnet will become saturated with port 135 requests.
While W32.Blaster.E.Worm cannot spread to the Windows NT or Windows Server 2003, unpatched computers running these operating systems may crash as a result of the worm's attempts to exploit them. However, if the worm is manually placed and executed on a computer running these operating systems, it can run and spread.
Due to the random nature of how the worm constructs the exploit data, this may cause the RPC service to crash if it receives incorrect data. This may manifest as svchost.exe, generating errors as a result of the incorrect data.
If the RPC service crashes, the default procedure under Windows XP and Windows Server 2003 is to restart the computer. To disable this feature, see step one of the Removal Instructions below.

Uses Cmd.exe to create a hidden remote shell process that will listen on TCP port 4444, allowing an attacker to issue remote commands on an infected system.

Listens on UDP port 69. When the worm receives a request from a computer to which it was able to connect using the DCOM RPC exploit, it will send mslaugh.exe to that computer and tell it to execute the worm.

If the current date is the 16th through the end of the month for the months of January to August, or if the current month is September through December, the worm will attempt to perform a DoS on kimble.org. However, the attempt to perform the DoS will succeed only if one the following conditions is true:
The worm runs on a Windows XP computer that was either infected or restarted during the payload period.
The worm runs on a Windows 2000 computer that was infected during the payload period and has not been restarted since it was infected.
The worm runs on a Windows 2000 computer that has been restarted since it was infected, during the payload period, and the currently logged in user is Administrator.

The DoS traffic has the following characteristics:
Is a SYN flood on port 80 of kimble.org.
Tries to send 50 HTTP packets every second.
Each packet is 40 bytes in length.
If the worm cannot find a DNS entry for kimble.org, it uses a destination address of

Some fixed characteristics of the TCP and IP headers are:
IP identification = 256
Time to Live = 128
Source IP address = a.b.x.y, where a.b are from the host ip and x.y are random. In some cases, a.b are random.
Destination IP address = dns resolution of "kimble.org"
TCP Source port is between 1000 and 1999
TCP Destination port = 80
TCP Sequence number always has the two low bytes set to 0; the 2 high bytes are random.
TCP Window size = 16384

The worm contains the following text, which is never displayed:

I dedicate this particular strain to me ANG3L - hope yer enjoying yerself and dont forget the promise for me B/DAY !!!!

Mitigating the DoS Payload
Network administrators can use the following recommendations to mitigate the DoS payload:
Reroute kimble.org to a special internal IP address: This will alert you to the infected machines if you have a server listening to catch the SYN flood.
Configure anti-spoofing rules on the routers, if this has not already been implemented: This will prevent a high percentage of packets from leaving the network. Using uRPF or egress ACLs would be effective.

removal instructions..
1.Disable System Restore (Windows XP).
2.Update the virus definitions.
3.End the Trojan process.
4.Run a full system scan and delete all the files detected as W32.Blaster.E.Worm.
5.Reverse the changes that the Trojan made to the registry.

This one is created by the same user.He wanna celebrate his/her birthday!!!!!!1

29-08-03, 10:30
So as long as you have the patch from the first Wormblaster you should be alright?

Lara Trent
29-08-03, 10:47
I have Blaster Warm a week ago. I think it's the same that your talking about lara_tx.

29-08-03, 18:07
He's been caught....