Worm:W32/Gurong.A

Installation

After the worm's file is run, it copies itself to the Windows System folder as wmedia16.exe and creates a startup key value for this file in the registry.

Rootkit

The worm is able to hide the following items:

• Processes
• Files
• Registry keys and values

When the worm is active, it hides its own process, file and launch point in the registry.The worm installs a call gate through \Device\PhysicalMemory to execute part of its code in kernel mode (ring 0). The kernel-mode code replaces the following function pointers from the system service table:

• NtClose
• NtCreateFile
• NtEnumerateKey
• NtEnumerateValueKey
• NtOpenFile
• NtQueryDirectoryFile

This allows it to hide files, registry keys and values. In addition, the worm is able to modify kernel-mode process structures to hide any process it specifies.

Propagation (email)

Before spreading, the worm looks for email addresses in the victim's Windows Address Book (WAB) file and also in files with the following extensions:

• adb
• asp
• dbx
• htm
• php
• pl
• sht
• tbb
• txt
• wab

The worm ignores email addresses that contains any of the following substrings:

• .aero
• .gov
• .mil
• accoun
• AccountRobot
• acketst
• admin
• alert
• anyone
• arin.
• avp
• berkeley
• borlan
• bsd
• bsd
• bugs
• ca
• certific
• contact
• example
• feste
• fethard
• fido
• foo.
• fraud
• fsf.
• gnu
• gold-certs
• google
• google
• gov.
• help
• hotmail
• iana
• ibm.com
• icrosof
• icrosoft
• ietf
• info
• inpris
• isc.o
• isi.e
• kernel
• linux
• linux
• listserv
• math
• me
• mit.e
• mozilla
• msn.
• mydomai
• no
• nobody
• nodomai
• noone
• not
• nothing
• ntivi
• page
• panda
• pgp
• postmaster
• privacy
• rating
• rfc-ed
• ripe.
• root
• ruslis
• samples
• secur
• sendmail
• service
• site
• soft
• somebody
• someone
• sopho
• submit
• support
• syma
• tanford.e
• the.bat
• unix
• unix
• usenet
• utgers.ed
• webmaster
• webmoney
• you
• your

The worm then constructs the email message used to deliver the worm's file by using the following "building blocks". The subject of the message can be one of the following:

• Greetings!
• Hello friend ;)
• Hey dear!
• Re: Hello
• Re: I got it! Try it now!
• Re[2]: wazzup bro
• Wazzap bro!!

The body text can be one of the following:

• Greetings! Check out my portfolio, please! Here is some my photos in the archive.
• Greetings. Here is some my nude photos in the attachment.
• Hello bro! Here is my new girlfriend's photo! Check it out!
• Hello buddy! Take a look at attachment! Here is my nude 17-yr sister!
• Hello! Here is NEW smiles pack for MSN messenger! It is really cool ;)
• Hello! I sent you new skype plug-in, as you wished.
• Hello! There is NEW plug-in for MSN. Try it out!
• Hey bro! Check out attachment! There is a new plug-in for skype!
• Hey dear! Here is my photos, as I promised.
• Hey friend! Try this new smiles pack for MSN messenger!
• Hey man! Take a look at attachment!
• Whatz up man! There is my nude 17-yr sister in the attachment!'

The infected attachment name can be any of the following:

• body
• conf_data
• doc
• document
• i_love_u
• i_luv_u
• port_imgs
• sex_girls
• sex_pics

Infected attachments can have the following extensions:

• bat
• cmd
• exe
• pif
• scr

The worm spoofs (fakes) the sender's email address. The following user names are used to compose the fake sender's address:

• adam
• alex
• alexey
• alice
• andrew
• anna
• bob
• boris
• brenda
• brent
• brian
• claudia
• craig
• cyber
• dan
• dave
• david
• debby
• den
• dmitry
• frank
• george
• gerhard
• helen
• ilya
• james
• jane
• jayson
• jerry
• jim
• jimmy
• joe
• john
• jose
• julie
• kevin
• lee
• leo
• linda
• linda
• maria
• marina
• mary
• matt
• michael
• mike
• nikolay
• olga
• peter
• ray
• robert
• sam
• sandra
• serg
• smith
• steve
• tom
• vlad
• vladimir

The following domain names are used to compose the fake sender's address:

• aol.com
• earthlink.net
• hotmail.com
• msn.com
• yahoo.com

Propagation (File sharing)

The worm copies itself to the shared folder of the peer-to-peer Kazaa client, with the following names:

• 0day_patch
• dcom_patches
• icq5
• lsas_patches
• msblast_patches
• office_crack
• skype_video
• strip-girl4.0c
• trillian_crack_all
• winamp5
• xp_activation

The extensions of the copied files are randomly selected from the following variants:

• bat
• exe
• pif
• scr

Registry Modifications

Creates these keys:

• [HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "WMedia16" = "%WinSysDir%\wmedia16.exe"