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Msblast.exe Worm


yodasarmpit
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You may have noticed there was a major worm attack across the web last night and is spreading very quicly.

If you always run a firewall or update windows regularly you should be OK.

The infected machines once connected to the web get a message telling you that you have 60 secs to save your work, it then counts down and reboots your system.

At this point thats the worst it does but newer versions may do a lot more damage.

Heres how to protect yourself.

To get rid of the worm, first thing to do is start your system in safe mode (press F8 on when booting up)

Go into C:/Windows/System32/ and deleate a file called MSBLAST.EXE (you can only do this in safe mode)

Now reboot.

Now make sure you switch on your firewall, then connect to the net and download the patch from Microsoft get it here http://microsoft.com/downloads/details.asp...&displaylang=en

You shouldn’t have any more problems.

For more info go here http://www.microsoft.com/downloads/search....en&categoryid=7

Brett

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Well the office has now been hit hard by MSBlast and as usual I am being forced to firefight due to no pro-active action being taken.

Don't suppose anyone knows a good piece of kit that exists in hardware form that we could plug into the system so any traffic coming into the office has to pass through and get virus checked at the point of entry/exit from the office ?

I guess it's time for me to make some suggestions to the network/software dept. again....

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I have heart failure every time a machine here reboots... we've only had one reported case at this site and that was a lab machine so not running anti-virus software and it turned out to be a different virus anyway. There are huge filters in place that means that anyone connecting remotely over OneRas/ISDN/ADSL has to wait 20 minutes to log on....oops...ahh well, tough! Being pro-active is goooooood although not totally effective as SMS has died so we can't deploy the patch...oh and you need SP2 to run the patch anyway so we need SMS to do that first but can't so will have to deploy manually. Can anyone say "overtime" :lol:

dub_boy- you are joking right??

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Easiest way to get rid of this as follows:

Download from Symantec website their removal tool, this removes the registry entries, the files, processes etc etc.

Then install either SP4 for windows 2000 or SP1 for Windows XP. You will then need to install the Microsoft MS03-026 RPC Vulnerablity Security Patch. This will stop the worm infecting your systems again. Then update your virus definitions.

Ryan - you can just block ports 69, 135 and 4444 and this will stop the worm traffic.

This security hole was first found in June and the MS03-026 patch has been around since early July, the report at the bottom of this mail first published on 16th July, so no blame can be laid on microsoft really, this worm exploits the fact that people don't keep their systems up to date.

Having said that, I did a bit of reverse engineering on the msblast executable and there are comments in the code at the bottom that say somthing like - "Bill, stop making too much money and sort your F**king software out".... lol

The security hole effects Windows NT4, 2000, XP and Server 2003 - check out the Microsoft Report on MS03-026 after this virus report.

Full Virus Report:

Virus Information

Name: W32/Lovsan.worm

Risk Assessment

- Home Users: Medium-On-Watch

- Corporate Users: Medium-On-Watch

Date Discovered: 8/11/2003

Date Added: 8/11/2003

Origin: Unknown

Length: 6,176 bytes

Type: Virus

SubType: Internet Worm

DAT Required: 4284

Virus Characteristics

This threat was proactively detected as a variant of Exploit-DcomRpc with the 4283 DAT files and 4.1.60+ scan engine. This detection requires the scanning of compressed executables to be enabled (VirusScan 7 provides the ability to disable this option, however it is enabled by default).

This threat exploits the MS03-026 vulnerability. The purpose of the virus is to spread to as many machines as possible. By exploiting an unplugged hole in Windows, the virus is able to execute without requiring any action on the part of the user. The worm also creates a remote access point, allowing an attacker to run system commands at their choosing.

When run, it scans a random IP range to look for vulnerable systems on TCP port 135. The worm attempts to exploit the DCOM RPC vulnerability on the found systems to create a remote Shell on TCP port 4444. It then instructs the system to download the worm to the %WinDir%\system32 directory and execute it. (The target system is issued a TFTP command to downloads the worm from the infected host system [TFTP UDP port 69].

Once run, the worm creates the registry key (may be either of the following):

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\

Run "windows auto update" = msblast.exe I just want to say LOVE YOU SAN!! bill

This will appear in regedit as:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\

Run "windows auto update" = msblast.exe

Indications of Infection

- Presence of unusual TFTP* files

- Presence of the file msblast.exe in the WINDOWS SYSTEM32 directory

- Error messages about the RPC service failing (causes system to reboot)

- The worm randomly opens 20 sequential TCP ports for listening. This is a constantly revolving range (ie. 2500-2520, 2501-2521, 2502-2522). The purpose of this action is unknown

Method of Infection

This worm spreads by exploiting a recent vulnerability in Microsoft Windows. The worm scans random ranges of IP addresses on port 135. Discovered systems are targeted. Exploit code is sent to those systems, instructing them to download and execute the file MSBLAST.EXE from a remote system via TFTP.

The worm contains a payload to initiate a Denial of Service attack against windowsupdate.com.

Computers that have up-to-date antivirus software will detect the worm executable upon download. However, unless the system has been (MS03-026) patched, it is susceptible to the buffer overflow attack. This means that the remote Shell will still get created on TCP port 4444, and the system may unexpectedly crash due upon receiving malformed exploit code.

Removal Instructions

All Users:

Use the 4284 DAT files for detection an removal. The 4283 DAT files will detect this threat as a variant of Exploit-DcomRpc. Infected systems must be patched prior to removal of the virus (see below).

Alternatively, the following EXTRA.DAT packages are available.

EXTRA.DAT

SUPER EXTRA.DAT

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

Microsoft Patches

It is imperative that infected systems are patched prior to disinfecting a system. Some systems may be in a “crash loop” where each time the system is restarted, SVCHOST.EXE crashes and the user has 60 seconds before the system restarts. This action can continue to happen even after the virus is removed if the patch is not applied.

Ensure that your system is not at risk from this exploited vulnerability:

Apply the MS03-026 patch to all vulnerable systems.

Stand alone remover

Stinger has been updated to include detection/removal of this threat.

Sniffer Customers: Download a Sniffer filter to detect W32/Lovsan.worm traffic (Sniffer Distributed 4.3 and Sniffer Portable 4.7.5).

Manual Removal Instructions

To remove this virus "by hand", follow these steps:

Apply the MS03-026 patch

Terminate the process msblast.exe

Delete the msblast.exe file from your WINDOWS SYSTEM32 directory (typically c:\windows\system32 or c:\winnt\system32)

Edit the registry

Delete the "windows auto update" value from

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\

Windows\CurrentVersion\Run

Additional Windows ME/XP removal considerations

Aliases

msblast.exe, tftp, W32.Blaster.Worm (Symantec), Win32.Poza (CA), WORM_MSBLAST.A (Trend)

Microsoft Report on MS03-026 Security Vulnerability in RPC Service

Buffer Overrun In RPC Interface Could Allow Code Execution (823980)

Originally posted: July 16, 2003

Revised: August 12, 2003

Summary

Who should read this bulletin: Users running Microsoft ® Windows ®

Impact of vulnerability: Run code of attacker’s choice

Maximum Severity Rating: Critical

Recommendation: Systems administrators should apply the patch immediately

End User Bulletin: An end user version of this bulletin is available at:

http://www.microsoft.com/security/security...ns/ms03-026.asp.

Affected Software:

Microsoft Windows NT® 4.0

Microsoft Windows NT 4.0 Terminal Services Edition

Microsoft Windows 2000

Microsoft Windows XP

Microsoft Windows Server™ 2003

Not Affected Software:

Microsoft Windows Millennium Edition

Technical details

Technical description:

Microsoft originally released this bulletin and patch on July 16, 2003 to correct a security vulnerability in a Windows Distributed Component Object Model (DCOM) Remote Procedure Call (RPC) interface. The patch was and still is effective in eliminating the security vulnerability. However, the “mitigating factors” and “workarounds” discussions in the original security bulletin did not clearly identify all of the ports by which the vulnerability could potentially be exploited. We have updated this bulletin to more clearly enumerate the ports over which RPC services can be invoked, and to ensure that customers who have chosen to implement a workaround before installing the patch have the information that they need to protect their systems. Customers who have already installed the patch are protected from attempts to exploit this vulnerability, and need take no further action.

In addition, the bulletin has also been updated to include information about Windows 2000 Service Pack 2 support for this patch.

Remote Procedure Call (RPC) is a protocol used by the Windows operating system. RPC provides an inter-process communication mechanism that allows a program running on one computer to seamlessly execute code on a remote system. The protocol itself is derived from the Open Software Foundation (OSF) RPC protocol, but with the addition of some Microsoft specific extensions.

There is a vulnerability in the part of RPC that deals with message exchange over TCP/IP. The failure results because of incorrect handling of malformed messages. This particular vulnerability affects a Distributed Component Object Model (DCOM) interface with RPC, which listens on RPC enabled ports. This interface handles DCOM object activation requests that are sent by client machines to the server. An attacker who successfully exploited this vulnerability would be able to run code with Local System privileges on an affected system. The attacker would be able to take any action on the system, including installing programs, viewing changing or deleting data, or creating new accounts with full privileges.

To exploit this vulnerability, an attacker would need to send a specially formed request to the remote computer on specific RPC ports.

Mitigating factors:

To exploit this vulnerability, the attacker would require the ability to send a specially crafted request to port 135, 139, 445 or 593 or any other specifically configured RPC port on the remote machine. For intranet environments, these ports would normally be accessible, but for Internet connected machines, these would normally be blocked by a firewall. In the case where these ports are not blocked, or in an intranet configuration, the attacker would not require any additional privileges.

Best practices recommend blocking all TCP/IP ports that are not actually being used, and most firewalls including the Windows Internet Connection Firewall (ICF) block those ports by default. For this reason, most machines attached to the Internet should have RPC over TCP or UDP blocked. RPC over UDP or TCP is not intended to be used in hostile environments such as the Internet. More robust protocols such as RPC over HTTP are provided for hostile environments.

To learn more about securing RPC for client and server please refer to http://msdn.microsoft.com/library/default....t_or_server.asp.

To learn more about the ports used by RPC, please refer to: http://www.microsoft.com/technet/prodtechn...rt4/tcpappc.asp

Severity Rating: Windows NT 4.0 Critical

Windows NT 4.0 Terminal Server Edition Critical

Windows 2000 Critical

Windows XP Critical

Windows Server 2003 Critical

The above assessment is based on the types of systems affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them.

Vulnerability identifier: CAN-2003-0352

Tested Versions:

Microsoft tested Windows Me, Windows NT 4.0, Windows NT 4.0 Terminal Services Edition, Windows 2000, Windows XP and Windows Server 2003, to assess whether they are affected by this vulnerability. Previous versions are no longer supported, and may or may not be affected by this vulnerability.

Frequently asked questions

Why have you revised this bulletin?

Subsequent to the release of this bulletin Microsoft has been made aware that additional ports involving RPC can be used to exploit this vulnerability. Information regarding these additional ports has been added to the mitigating factors and the Workaround section of the bulletin.

If I have installed the patch provided with the original bulletin, am I still protected?

Yes. There has been no update to the patch itself, and the patch will still correct the vulnerability. This additional information is being provided to those customers who may require a temporary workaround until they can apply the patch.

Is the patch supported on Windows 2000 Service Pack 2?

This security patch will install on Windows 2000 Service Pack 2. However, Microsoft no longer supports this version, according to the Microsoft Support Lifecycle policy found at http://support.microsoft.com/lifecycle. In addition, this security patch has only received minimal testing on Windows 2000 Service Pack 2. Customers are strongly advised to upgrade to a supported service pack as soon as possible. Microsoft Product Support Services will support customers who have installed this patch on Windows 2000 Service Pack 2 if a problem results from installation of the patch.

What’s the scope of the vulnerability?

This is a buffer overrun vulnerability. An attacker who successfully exploited this vulnerability could gain complete control over a remote computer. This would give the attacker the ability to take any action on the server that they want. For example, and attacker could change Web pages, reformat the hard disk, or add new users to the local administrators group.

To carry out such an attack, an attacker would require the ability to send a malformed message to the RPC service and thereby cause the target machine to fail in such a way that arbitrary code could be executed.

What causes the vulnerability?

The vulnerability results because the Windows RPC service does not properly check message inputs under certain circumstances. This particular failure affects an underlying Distributed Component Object Model (DCOM) interface, which listens on RPC enabled ports. By sending a malformed RPC message, an attacker could cause the RPC service on a machine to fail in such a way that arbitrary code could be executed. interface with RPC on the remote machine to fail in such a way that arbitrary code could be executed.

What is DCOM?

The Distributed Component Object Model (DCOM) is a protocol that enables software components to communicate directly over a network. Previously called "Network OLE," DCOM is designed for use across multiple network transports, including Internet protocols such as HTTP. More information about DCOM can be found at the following website:

http://www.microsoft.com/com/tech/dcom.asp

What is RPC (Remote Procedure Call)?

Remote Procedure Call (RPC) is a protocol that a program can use to request a service from a program located on another computer in a network. RPC helps with interoperability because the program using RPC does not have to understand the network protocols that are supporting communication. In RPC, the requesting program is the client and the service-providing program is the server. What is COM Internet Services (CIS) and RPC over HTTP?

Component Object Model (COM) Internet Services (CIS) introduced support for the Distributed COM (DCOM) transport protocol known as Tunneling Transmission Control Protocol (TCP) that allows DCOM to operate over TCP port 80.

CIS and it’s follow-on, RPC over HTTP, allows a client and a server to communicate in the presence of most proxy servers and firewalls, thereby enabling COM-based Internet scenarios.

How do I know if I have CIS installed?

The best way to determine if you have CIS or RPC over HTTP installed on the computer is to search your computer for the file rpcproxy.dll. If the file is found, then CIS is installed on the computer.

To search for a specific file on your computer:

Start--> Run-->Search--> For Files or Folders… and enter the name of the file your are looking for. It may take a few minutes for the search to run, depending on the size of your hard drive.

What's wrong with Microsoft’s implementation of Remote Procedure Call (RPC)?

There is a flaw in a part of RPC that deals with message exchange over TCP/IP. A failure results because of incorrect handling of malformed messages. This particular failure affects an underlying DCOM interface, which listens on TCP/IP port 135, and can be reached via ports 139, 445 and 593. By sending a malformed RPC message, an attacker could cause the RPC service on a machine to fail in such a way that arbitrary code could be executed.

Is this a flaw in the RPC Endpoint Mapper?

No - The flaw actually occurs in a low level DCOM interface within the RPC process. The RPC endpoint mapper allows RPC clients to determine the port number currently assigned to a particular RPC service. An endpoint is a protocol port or named pipe on which the server application listens to for client remote procedure calls. Client/server applications can use either well-known or dynamic ports.

Security Bulletin MS03-010 also involved RPC yet you could not fix that vulnerability on Windows NT 4.0. How were you able to fix this vulnerability on Windows NT 4.0?

The flaw in this case lies in an underlying DCOM interface to RPC, and not the overall RPC implementation or the RPC Endpoint Mapper itself. As a result, it was possible to address this vulnerability in Windows NT 4.0 without needing to rearchitect significant portions of the Windows NT 4.0 operating system, as would have been required by a Windows NT 4.0 patch for security bulletin MS03-010.

What could this vulnerability enable an attacker to do?

An attacker who successfully exploited this vulnerability would be able to run code with Local System privileges on an affected system. The attacker would be able to take any action on the system, including installing programs, viewing changing or deleting data, or creating new accounts with full privileges.

How could an attacker exploit this vulnerability?

An attacker could seek to exploit this vulnerability by programming a machine that could communicate with a vulnerable server over RPC to send a specific kind of malformed RPC message. Receipt of such a message could cause the RPC service on the vulnerable machine to fail in such a way that it could execute arbitrary code.

Who could exploit the vulnerability?

Any user who could deliver a TCP request to an RPC interface to an affected computer could attempt to exploit the vulnerability. Because RPC requests are on by default in all versions of Windows, this in essence means that any user who could establish a connection with an affected computer could attempt to exploit the vulnerability.

It could also be possible to access the affected component through another vector, such as one that would involve logging onto the system interactively or by using another application similar that passed parameters to the vulnerable component either locally or remotely.

What does the patch do?

The patch corrects the vulnerability by altering the DCOM interface to properly check the information passed to it.

Workarounds:

Are there any workarounds that can be used to help block exploitation of this vulnerability while I am testing or evaluating the patch?

Yes. Although Microsoft urges all customers to apply the patch at the earliest possible opportunity, there are a number of workarounds that can be applied to help prevent the vector used to exploit this vulnerability in the interim. There is no guarantee that the workarounds will block all possible attack vectors.

It should be noted that these workarounds should be considered temporary measures as they just help block paths of attack rather than correcting the underlying vulnerability.

Block UDP ports 135, 137, 138, 445 and TCP ports 135, 139, 445, 593 at your firewall and disable COM Internet Services (CIS) and RPC over HTTP, which listen on ports 80 and 443, on the affected machines.

These ports are used to initiate an RPC connection with a remote computer. Blocking them at the firewall will help prevent systems behind that firewall from being attacked by attempts to exploit these vulnerabilities. You should also be sure and block any other specifically configured RPC port on the remote machine.

If enabled, CIS and RPC over HTTP allow DCOM calls to operate over TCP ports 80 (and 443 on XP and Windows Server 2003). Make sure that CIS and RPC over HTTP are disabled on all the affected machines.

More information on how to disable CIS can be found in Microsoft Knowledge Base Article 825819.

For information regarding RPC over HTTP, see http://msdn.microsoft.com/library/default....tp_security.asp.

Use Internet Connection Firewall (only available on XP and Windows Server 2003) and disable COM Internet Services (CIS)and RPC over HTTP, which listen on ports 80 and 443, on the affected machines.

If you are using the Internet Connection Firewall in Windows XP or Windows Server 2003 to protect your Internet connection, it will by default block inbound RPC traffic from the Internet. Make sure that CIS and RPC over HTTP are disabled on all affected machines.

More information on how to disable CIS can be found in Microsoft Knowledge Base Article 825819.

For information regarding RPC over HTTP, see http://msdn.microsoft.com/library/default....tp_security.asp.

Block the affected ports using an IPSEC filter and disable COM Internet Services (CIS) and RPC over HTTP, which listen on ports 80 and 443, on the affected machines.

You can secure network communications on Windows 2000-based computers if you use Internet Protocol Security (IPSec). Detailed information on IPSec and how to apply filters can be found in Microsoft Knowledge Base Article 313190 and 813878. Make sure that CIS and RPC over HTTP are disabled on all affected machines.

More information on how to disable CIS can be found in Microsoft Knowledge Base Article 825819.

For information regarding RPC over HTTP, see http://msdn.microsoft.com/library/default....tp_security.asp.

Disable DCOM on all affected machines

When a computer is part of a network, the DCOM wire protocol enables COM objects on that computer to communicate with COM objects on other computers. You can disable DCOM for a particular computer to help protect against this vulnerability, but doing so will disable all communication between objects on that computer and objects on other computers.

If you disable DCOM on a remote computer, you will not be able to remotely access that computer afterwards to re-enable DCOM. To re-enable DCOM, you will need physical access to that computer.

Information on how to disable DCOM is available in Microsoft Knowledge Base Article 825750.

Note: For Windows 2000, the methods described above to disable DCOM will only work on systems running Service Pack 3 or later. Customers using Service Pack 2 or below should upgrade to a later Service Pack or use one of the other workarounds.

Cheers - sorry about monster post...

Steve.

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well i got to say that this Virus as got to be one of the biggest of e'm all infecting thousands of NT based machines, since i work for a microsoft certified call center company

in the UK and having reached 40.000 calls over a 2 day period is phenomenal.

also i hear about this power cut knocking out 80% of the states down to a blown

fuse :rolleyes: its a bit of a coincidence that we get a hit by a major virus then get hit

by a major power cut, I wonder if the power stations was running NT based systems

and its a cover up for M$ :angry:

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It's a nightmare... hate it... i'm in the middle of rolling out ADSL to home workers and due to all this virus alert they've cut the VPN tunnel so I've talked everyone into getting this service then the day they go live we cut em off LMAO. They love me right now and it's sooooooo not my fault!!

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Don't suppose anyone knows a good piece of kit that exists in hardware form that we could plug into the system so any traffic coming into the office has to pass through and get virus checked at the point of entry/exit from the office ?

I guess it's time for me to make some suggestions to the network/software dept. again....

hi peeps, we use ca inoculateit. we have never had an virus infection in 7 years. But this is a nasty bugger managed to crash out two servers and 30 workstations. The crashes were due to the virus scanners blocking the attack and stopping the infection and dcom services grinding to a halt. a lot of our core apps depend on dcom hence whhy the workstations bombed out. so at the end of the day we still had zero infections. not really hardware Ryan but damn good peice of software :thumbsup:

Indications of Infection - Steve

also on pc's where an attempted infection has failed you will get svchost.exe crash but the pc wont reboot. the workstation just sits there but office apps etc. stop functioning properly etc. Restart the pc and everything is ok again.

Apologies if this has already been mentioned, havent read the thread from top to bottom fully yet :rolleyes:

Surinder...

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Make sure ya sort it before it gets ya. :blink:

my workplace win2k prof network was wrecked within minutes of it being released. (wednesday afternoon) :!Removed!: :!Removed!:

sorted now, if ya use mcafee virus scan there is a patch on their site to sort it. :thumbsup:

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