F-Secure Virus Descriptions : Vesser

[Summary] | [Detailed Description] | [Detection]

NAME:	Vesser
ALIAS:	W32.HLLW.Deadhat

Summary

Vesser is a network worm that was found on February 7th, 2004.

This worm spreads through the backdoor of Mydoom.A and Mydoom.B as well as through a Peer-to-Peer application called SoulSeek.

Detailed Description

System Infection

When Vesser enters a system it copies itself to the the Windows System Directory as 'sms.exe' and adds the file to the registry as

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\KernelFaultChk

Network Propagation

Vesser mainly targets computers that have previously been infected with the Mydoom.A or Mydoom.B worms. Vesser scans for the backdoors in those worms on IP addresses. While doing that it connects to TCP ports 1080. 3127 and 3128 and tries to copy itself there in a specially-crafted package.

Once it has successfully penetrated a computer it removes the previous Mydoom infection:

It removes the following registry keys and values:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\TaskMon HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Explorer

HKCU\CLSID\{E6FB5E20-DE35-11CF-9C87-00AA005127ED}\InprocServer32 HKCR\CLSID\{E6FB5E20-DE35-11CF-9C87-00AA005127ED}\InprocServer32

The worm terminates processes with names that contain any of the following strings:

 "document"
 "readme"
 "doc"
 "text"
 "file"
 "data"
 "test"
 "message"
 "body"
 "taskmon"
 "xsharez_scanner"
 "BlackIce_Firewall_Enterpriseactivation_crack"
 "zapSetup_95_693"
 "MS59-56_hotfix"
 "winamp0"
 "NessusScan_pro"
 "attackXP-6.71"

Propagation Through SoulSeek

If the infected computer has a copy of the SoulSeek file sharing application the worm copies itself to the shared folder with different catchy names for users to download:

 "WinXPKeyGen.exe"
 "Windows2003Keygen.exe"
 "mIRC.v6.12.Keygen.exe"
 "Norton.All.Products.KeyMkr.exe"
 "F-Secure.Antivirus.Keymkr.exe"
 "FlashFXP.v2.1.FINAL.Crack.exe"
 "SecureCRTPatch.exe"
 "TweakXPProKeyGenerator.exe"
 "FRUITYLOOPS.SPYWIRE.FIX.EXE"
 "ALL.SERIALS.COLLECTION.2003-2004.EXE"
 "WinRescue.XP.v1.08.14.exe"
 "GoldenHawk.CDRWin.v3.9E.Incl.Keygen.exe"
 "BlindWrite.Suite.v4.5.2.Serial.Generator.exe"
 "Serv-U.allversions.keymaker.exe"
 "WinZip.exe"
 "WinRar.exe"
 "WinAmp5.Crack.exe"

Termination of Security Software

Vesser has a long list of processes that it tries to terminate if found running in the memory:

 "_avp"
 "kfp4gui"
 "kfp4ss"
 "zonealarm"
 "Azonealarm"
 "avwupd32"
 "avwin95"
 "avsched32"
 "avp"
 "avnt"
 "avkserv"
 "avgw"
 "avgctrl"
 "avgcc32"
 "ave32"
 "avconsol"
 "apvxdwin"
 "ackwin32"
 "blackice"
 "blackd"
 "dv95"
 "espwatch"
 "esafe"
 "efinet32"
 "ecengine"
 "f-stopw"
 "frw"
 "fp-win"
 "f-prot95"
 "f-prot"
 "fprot"
 "f-agnt95"
 "gibe"
 "iomon98"
 "iface"
 "icsupp"
 "icssuppnt"
 "icmoon"
 "icmon"
 "icloadnt"
 "icload95"
 "ibmavsp"
 "ibmasn"
 "iamserv"
 "iamapp"
 "kpfw32"
 "nvc95"
 "nupgrade"
 "nupdate"
 "normist"
 "nmain"
 "nisum"
 "navw"
 "navsched"
 "navnt"
 "navlu32"
 "navapw32"
 "zapro"

Remote Update Feature

Once the worm has activated it opens TCP port 2766 and awaits for clients. Connecting clients must be authenticated with a crypto key. If the authentication is successful the backdoor accepts a file for upload and executes it on the system.

IRC Backdoor

The IRC backdoor component connects to a predefined IRC server and listens on a specific channel for commands from the author. The backdoor supports different commands to download and execute arbitrary programs on the infected computer.

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Detection

Detection in F-Secure Anti-Virus was published on February 7th, 2004 in update:

[FSAV_Database_Version]

Version=2004-02-07_1

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Write-up: Gergely Erdelyi, February 9th, 2004;

F-Secure Corporation