What
is the MSBLAST.K?
Also known as: W32.Blaster.Worm, WORM_MSBLAST.H,
Worm.Win32.Lovesan.a, W32/Lovsan.worm.gen
MSBLAST.K 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 computers.
While Windows NT and Windows 2003 servers are
vulnerable to the exploit if they are not
properly patched, the worm is not coded to
replicate to those systems. This worm attempts to
download the mschost.exe file into the %Windir%\System32
folder, and then execute it.
MSBLAST.K does not have a mass-mailing
functionality.
We recommend 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 the Microsoft Windows Update Web
server (windowsupdate.com). This is an attempt to
prevent you from applying a patch on your
computer against the DCOM RPC vulnerability.
How
Does MSBLAST.K Worm Infect My System?
When it is executed, MSBLAST.K performs the
following actions:
- Checks to see whether a computer is already
infected and if the worm is running. If so,
the worm will not infect the computer a second
time.
- Adds the value:
"windows shellext.32"="mschost.exe"
to the registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\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.
- 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 it was able
to connect to using the DCOM RPC exploit, it
sends mschost.exe to that computer and then
executes it.
- 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 attack 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:
- Sends a SYN flood on TCP port 80 of
windowsupdate.com.
- 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 255.255.255.255.
Some fixed characteristics of the TCP and
IP headers are:
- IP identification is 256.
- Time to live is 128.
- Source IP address is a.b.x.y, where a
and b are from the host IP and x and y are
random. In some cases, a.b are random as
well.
- Destination IP address is the DNS
resolution of "windowsupdate.com"
- TCP source port is between 1000 and
1999.
- TCP destination port is 80.
- TCP sequence number always has the two
low bytes set to 0 The two high bytes are
random.
- TCP window size is 16384.
The worm contains the following text in the code:
Can you hear me? I LOVE YOU SAN!!
Sucky gates why do you made this windows?
Stop fooling around and make good things!!!
How to Remove the MSBLAST.K worm?
Kaspersky Internet Security Can Prevent You From Virus and Intrusion.
If Kaspersky detects MSBLAST.K during the
scan, it will AUTOMATICALLY offer you the option
of deleting it. Do this by following the
program's instructions.
Follow these steps
in removing the MSBLAST.K worm.
1. Applying Patches
Apply the patches issued by Microsoft from the
following page: Microsoft
Security Bulletin MS03-026
2. Disabling System Restore (Windows Me/XP)
For instructions on how to turn off System
Restore, read your Windows documentation, or one
of the following articles: "How
to disable or enable Windows Me/XP System Restore".
3. Updating the Virus Definitions
If you do not know which anti-virus software
can provide strong protection for you, Kaspersky Internet Security is recommended.
4. Ending the Worm process
- Press Ctrl+Alt+Delete once.
- Click Task Manager.
- Click the Processes tab.
- Double-click the Image Name column header to
alphabetically sort the processes.
- Scroll through the list and look for
mschost.exe.
- If you find the file, click it, and then
click End Process.
- Exit the Task Manager.
5. Scanning for and deleting the infected
files
- Start your Kaspersky Internet Security and make sure that it is
configured to scan all the files.
- Run a full system scan.
- If any files are detected as infected with MSBLAST.K,
click Delete.
6. Reversing the changes made to the registry
- Click Start, and then click Run. (The Run
dialog box appears.)
- Type regedit
Then click OK. (The Registry Editor opens.)
- Navigate to the key:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
- In the right pane, delete the value:
"windows shellext.32"="mschost.exe"
- Exit the Registry Editor
How to Disinfect My Computer from Worms?
In order to keep your computer protected, bear
the following tips in mind:
- If you have filtering tools installed,
configure them to reject messages with the
characteristics described above. If, in spite
of doing this, you receive the message that
contains the virus: do not open it, do not run
the attached file and delete it, making sure
that you also delete it from the Deleted
Items folder.
- Install a good antivirus in your computer.
Select Kaspersky Internet Security to get the Kaspersky antivirus solution that best suits your needs.
- Keep your antivirus updated. If automatic
updates are available, configure your
antivirus to use them.
- Keep your permanent antivirus protection
enabled at all times.
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Detect and Removal Instruction for Other
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