Email-Worm.Win32.Hybris

Class Email-Worm
Platform Win32
Description

Technical Details

This is an Internet worm that spreads attached to e-mail messages. The worm works under Win32 systems only. The worm contains components (plugins) in its code
that are executed depending on the worm’s needs, and these components can be upgraded from an Internet Web site.

The major worm versions are encrypted with a semi-polymorphic encryption loop.

The worm contains the text strings:

HYBRIS
(c) Vecna

The Worm Runs

The main worm target on a computer is the WSOCK32.DLL library. While infecting
this file, the worm:

  • writes itself to the end of the last file section
  • hooks “connect”, “recv”, and “send” functions
  • modifies the DLL entry routine address (a routine that is activated when a DLL file is being loaded) and encrypts the original entry routine

If the worm is not able to infect WSOCK32.DLL (in case it is in use and is locked for writing), the virus creates a copy of that library (a copy of WSOCK32.DLL
with random name), infects it and writes a “rename” instruction to WININIT.INI file. As a result, WSOCK32.DLL will be replaced with an infected image upon the next Windows startup.

The worm also creates its copy with a random name in the Windows system directory and registers it in the RunOnce registry key:

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunOnce    {Default} = %WinSystem%WormName

or

HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunOnce    {Default} = %WinSystem%WormName

where %WinSystem% is the Windows system directory, and “WormName” is a random eight symbols name, for example:

CCMBOIFM.EXE
LPHBNGAE.EXE
LFPCMOIF.EXE

There is only possible reason for registering an additional worm copy in the “RunOnce” registry key: in case WSOCK32.DLL was not infected during the first worm run, and its infected copy was not created because of some reason, the “RunOnce” worm copy will complete the task upon the next Windows restart.

Infected WSOCK32.DLL

The worm intercepts Windows functions that establish a network connection, including the Internet. The worm intercepts data that are sent and received, and scans them
for e-mail addresses. When an address(es) is/are detected, the worm waits for some time and then sends an infected message to that/those address(es).

Plugins

The worm’s functionality depends on the plugins that are stored in worm body encrypted with a RSA-like strong crypto algorithm with a 128-bit key. There are
up to 32 plugins that can be found in different worm versions. These plugins perform different actions that can be updates from a Web page:

http://pleiku.vietmedia.com/bye/

so the complete worm functionality depends only on its host that is able to upgrade plugins on a Web page. The plugins on a page are encrypted with RSA-like crypto too.

The worm also updates its plugins by the using alt.comp.virus newsgroup. The worm, being active on a machine, connects to a news server (by using one of randomly selected servers – there are more than 70 addresses in the list), converts its plugins to newsgroup messages and posts them there. The Worm’s messages have a random-like Subject, for example:

encr HVGT GTeLKzurGbGvqnuDqbivKfCHWbizyXiPOvKD
encr CMBK bKfOjafCjyfWnqLqzSTWTuDmfefyvurSLeXGHqR
text LNLM LmnajmnKDyfebuLuPaPmzaLyXGXKPSLSXWjKvWnyDWbGH
text RFRE rebibmTCDOzGbCjSZ

where first four chores are plugin “name” and following four chores are an encoded plugin “version”. As well as sending, the worm reads such messages from alt.comp.virus, obtains the plugin “name” and “version” and compares them with plugins that are currently used by the worm. In case the newsgroup has a message with a higher plugin version, the worm extracts it and replaces the existing one. So the worm uses alt.comp.virus to upgrade its plugins.

The worm also creates these plugins as disk files in the Windows system directory. They also have a random name, but the worm keeps being able to access them. The names may look as follow:

BIBGAHNH.IBG
DACMAPKO.ACM
GAFIBPFM.AFI
IMALADOL.MAL
MALADOLI.ALA

There are several different known plugins that:

1. Infect all ZIP and RAR archives on all available drives from C: till Z:. While infecting, the worm renames EXE files in the archive with a .EX$ extension
and adds its copy with a .EXE extension to the archive (companion method of infection).

2. Send messages with encoded plugins to the “alt.comp.virus” neewsgroup, and obtains new plugins from there.

3. Spread virus to remote machines that have a SubSeven backdoor Trojan installed. The plugin detects such machines on the Net, and using SubSeven commands, uploads a worm copy to the machine and spawns it in there.

4. Encrypt worm copies with a polymorphic encryption loop before sending the copy attached to an e-mail.

5. Depending on system date and time (on September 16 and 24, and on 59 minute of each hour starting from year 2001 – in known plugins) the “spirale” effect is run.

The plugin creates random 8-bytes .EXE name in Windows system directory, unpacks “spirale effect” EXE code to there, and registers that file in the system:

under Win9x: in WIN.INI file in [windows] “run=” line
under WinNT: in system registry in “Run=” key

6. Affects DOS EXE and Windows PE EXE files. The worm affects them so that they become to be worm droppers. When run they drop worm EXE file to TEMP directory and execute it.

While affecting DOS EXE file the plugin adds dropper code and worm body to the end of the file. These files are disinfectable.

While affecting Windows PE EXE file the plugin overwrites file code section to get a gap for worm code, and writes worm dropper code to that gap (if is has enough size). The plugin doesn’t touch file header (including entry point address), and does not increase file size. Moreover, it has a anti-CRC (chechsum) routine that fill special data in plugin code so that file CRC becomes the same for few common used CRC algorithms. That means, that some integrity checkers will not detect changes in affected files: the file length and file body CRC stay the same as on clean file.

When such PE EXE file is run, the dropper code drops and activates the worm, then restores (unpacks) code section and returns control to the host file.

7. Randomly select a Subject, Message text and Attach name while sending the worm copies with e-mail messages:

From:

Hahaha [hahaha@sexyfun.net]

Subjects:

Snowhite and the Seven Dwarfs – The REAL story!

Branca de Neve porn�!

Enanito si, pero con que pedazo!

Les 7 coquir nains

Message texts:

C’etait un jour avant son dix huitieme anniversaire. Les 7 nains, qui avaient aid� ‘blanche neige’ toutes ces ann�es apr�s qu’elle se soit enfuit de chez sa belle m�re, lui avaient promis une *grosse* surprise. A 5 heures comme
toujours, ils sont rentr�s du travail. Mais cette fois ils avaient un air coquin…

Today, Snowhite was turning 18. The 7 Dwarfs always where very educated and polite with Snowhite. When they go out work at mornign, they promissed a *huge* surprise. Snowhite was anxious. Suddlently, the door open, and the Seven Dwarfs enter…

Faltaba apenas un dia para su aniversario de de 18 aTos. Blanca de Nieve fuera siempre muy bien cuidada por los enanitos. Ellos le prometieron una *grande* sorpresa para su fiesta de compleaTos. Al entardecer, llegaron. Tenian un brillo incomun en los ojos…

Faltava apenas um dia para o seu aniversario de 18 anos. Branca de Neve estava muito feliz e ansiosa, porque os 7 an�es prometeram uma *grande* surpresa. As cinco horas, os an�ezinhos voltaram do trabalho. Mas algo nao estava bem… Os sete an�ezinhos tinham um estranho brilho no olhar…

Attach names:

enano.exe
enano porno.exe
blanca de nieve.scr
enanito fisgon.exe

sexy virgin.scr
joke.exe
midgets.scr
dwarf4you.exe

blancheneige.exe
sexynain.scr
blanche.scr
nains.exe

branca de neve.scr
atchim.exe
dunga.scr
an�o porn�.scr

As well as (depending on the plugin version):

The message Subject is a random combination of:

 Anna             +  sex
 Raquel Darian       sexy
 Xena                hot
 Xuxa                hottest
 Suzete              cum
 famous              cumshot
 celebrity rape      horny
 leather             ... e.t.c.

Attach name:

Anna.exe
Raquel Darian.exe
Xena.exe
Xuxa.exe
Suzete.exe
famous.exe
celebrity rape.exe
leather.exe
sex.exe
sexy.exe
hot.exe
hottest.exe
cum.exe
cumshot.exe
horny.exe
anal.exe
gay.exe
oral.exe
pleasure.exe
asian.exe
lesbians.exe
teens.exe
virgins.exe
boys.exe
girls.exe
SM.exe
sado.exe
cheerleader.exe
orgy.exe
black.exe
blonde.exe
sodomized.exe
hardcore.exe
slut.exe
doggy.exe
suck.exe
messy.exe
kinky.exe
fist-fucking.exe
amateurs.exe

The attached file name may also be a random eight bytes .EXE name, for example:

ADELHHAD.EXE
CFIMMHAG.EXE
DIEOPIDI.EXE
EABLLNEA.EXE
FKPODKFK.EXE
HJEOINHJ.EXE
OGNNFEOG.EXE
PFFCKEPF.EXE

Effect