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Wurmark.L

Classification

Category: Malware

Type: Worm

Aliases: Wurmark.L, Email-Worm.Win32.Wurmark.l

Summary


Wurmark.L is an email worm that spreads using several different languages. It also drops a variant of Rbot on the infected system.

Removal


Automatic action

Based on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.

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Technical Details


Installation to system

When run, the worm drops the following three files from its resource:

bx.exe
bszip.dll
ANSMTP.DLL
 

'bx.exe' is a copy of Rbot. 'bszip.dll' and 'ANSMTP.DLL' are used later in email spreading. The work also writes the following files in the Windows system folder:

cmd.com
regedit.com
taskkill.com
tasklist.com
tracert.com
ping.com
netstat.com
 

The contents of these files are characters 'MZ'. As 'com' extension is evaluated before 'exe' in Windows program execution, this trick tries to disable the execution of above programs with 'exe' extension.

The worm executes 'bx.exe' which installs itself in system. This file is a variant of Rbot. When 'bx.exe' is run, it copies itself as 'winis.exe' in the Windows system directory and adds the following registry keys:

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
"IE Runtimes" = "%SysDir%\winis.exe"
 

This ensures that it will be executed at next system startup. The bot can be used as a backdoor, collecting system information, logging keystrokes, relaying spam and for various other purposes.

The worm also opens a jpg-file from predefined URL. The picture looks like this:

email spreading

Wurmark.L gathers email addresses from the MSN messenger and Yahoo IM client contact lists. The worm uses the dropped SMTP component (ANSMTP.DLL) to send infected messages. It can construct the messages in 7 different languages. The language is selected using the locale of the infected computer.

Here are the possible english messages:

Attachment Returned
This file was rejected by the recipient

You suck!
I have enclosed why you suck and your not going to like it :@

My new details
Hi i've changed email address if you would like to
 keep in contact i have enclosed my new details

Party Invite!!
You have been invited to my party
 please download the details and tell me if you
 will be able to make it , Thanks!
 

Here are the possible german messages:

Zubeh r Ging
Diese Akte wurde von der Empf nger zur ckgewiesen

Sie saugen!
Ich habe umgeben, warum Sie saugen und Ihr Gehen nicht zu wie ihm :@

Meine neuen Details
Hallo nderte ive email address, wenn Sie zu m chten
 Unterhalt im Kontakt habe ich meine neuen Details umgeben

Beteiligtes Laden!!
Sie sind zu meinem Beteiligten eingeladen worden
 ddownloaden Sie bitte die Details und erkl ren Sie mir
 wenn Sie in der LageSIND, es zu bilden, Dank!
 

Here are the possible french messages:

L'Attachement Est retourn
Ce dossier a rejet par le destinataire

Vous sucez!
J'ai enferm pourquoi vous sucez et votre ne pas aller comme lui :@

Mes nouveaux d tails
Bonjour l'ive a chang le email address si vous voudriez
 subsistance en contact j'ai joint mes nouveaux d tails

La Partie Invitent!!
Vous avez invit ma partie t chargez
 svp les d tails et me dites si vous pourrez la

faire, merci!
 

Possible italian messages:

Il Collegamento Ha rinviato
Questa lima stata rifiutata dal destinatario

Succhiate!
Ho accluso perch succhiate e vostro non andare come ad esso :@

I miei nuovi particolari
Hi il ive ha cambiato il email address se gradiste a
 conservazione in contatto ho accluso i miei nuovi particolari

Il Partito Invita!!
Siete stati invitati al mio partito prego
 trasferite i particolari dal sistema centrale
 verso i satelliti e mi dite se potrete farlo, ringraziamenti!
 

Possible portuguese messages:

O Acess rio Retornou
Esta lima foi rejeitada pelo receptor

Voc suga!
Eu inclu porque voc suga e seu n o lhe ir como :@

Usted aspira!
He incluido porqu usted aspira y el su no ir como a l :@

O Partido Convida!!
Voc foi convidado a meu partido download por
 favor os detalhes e diz-me se voc pudesse
o
 fazer, agradecimentos!
 

Possible spanish messages:

El Accesorio Volvi
Este archivo fue rechazado por el recipiente

Usted aspira!
He incluido porqu usted aspira y el su no ir como a l :@

Mis nuevos detalles
Hi el ive cambi email address si usted quisiera a
 mantener contacto he incluido mis nuevos detalles

El Partido Invita!!
Le han invitado a mi partido descarga por favor
 los detalles y me dice si usted puede hacerlo,
 gracias!
 

Possible dutch messages:

Het aanhechtsel Keerde Terug
Dit bestand werd door de ontvanger afgekeurd

U zuigt!
Ik heb waarom u zuigt bijgevoegd en uw gaand alsof het niet :@

Mijn nieuwe details
Hi veranderde ive email aanspreekt of u van naar zou houden
 Hou in contact ik heb bijgevoegd mijn nieuwe details bij

De partij Uitnodig!!
U bent naar mijn partij alstublieft download de details

uitgenodigd worden en vertel mij indien u hem zult kunnen

maken, Bedankt!
 

Attachment name is selected from the following list:

Party.pif
File.pif
Corrupt.pif
details.pif
Party.scr
File.scr
Corrupt.scr
details.scr
 

The file is packed inside 'File.zip' which is the actual attachment in the email.