Home > Threat descriptions >

Email-Worm:W32/Sober.L

Classification

Category: Malware

Type: -

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

Summary


Sober.L worm was seeded in emails on 7th of March 2005. It has less functionality than the previous variant, composing a smaller amount of different messages. Sober.L sends itself as an attachment in email messages with English or German texts.

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.

Knowledge Base

Find the latest advice in our Community Knowledge Base.

About the product

See the manual for your F-Secure product on the Help Center.

Contact Support

Chat with or call an expert for help.

Submit a sample

Submit a file or URL for further analysis.

Technical Details


The worm is written in Visual Basic. The worm's file is a modified UPX packed PE executable about 45 kilobytes long. The unpacked worm's file size is around 142 kilobytes. The worm adds random garbage to the end of its file every time it installs itself on a computer.

Installation to system

When the worm's file is started it opens Write text editor with the following text as a decoy:

When the worm's file is run, it copies itself as "smss.exe" into the %WinDir%\msagent\system\ folder, created by the worm.

Sober.L worm adds startup keys for "smss.exe" in System Registry:

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
" Services.dll" = "%WinDir%\msagent\system\smss.exe"
 

Also the worm drops the text file 'read.me' file to Windows folder.

Spreading in emails

The worm sends different types of email messages with English and German texts and its file attached. The attachment is a ZIP archive containing the worm's executable.

Before spreading the worm scans files with certain extensions on all hard disks to harvest email addresses. Files with the following extensions are scanned:

pmr
phtm
stm
slk
inbox
imb
csv
bak
imh
xhtml
imm
imh
cms
nws
vcf
ctl
dhtm
cgi
pp
ppt
msg
jsp
oft
vbs
uin
ldb
abc
pst
cfg
mdw
mbx
mdx
mda
adp
nab
fdb
vap
dsp
ade
sln
dsw
mde
frm
bas
adr
cls
ini
ldif
log
mdb
xml
wsh
tbb
abx
abd
adb
pl
rtf
mmf
doc
ods
nch
xls
nsf
txt
wab
eml
hlp
mht
nfo
php
asp
shtml
dbx
 

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

ntp-
ntp@
ntp.
info@
test@
@www
@from.
support
smtp-
@smtp.
gold-certs
ftp.
.dial.
.ppp.
anyone
subscribe
announce
@gmetref
sql.
someone
nothing
you@
user@
reciver@
somebody
secure
whatever@
whoever@
anywhere
yourname
mustermann@
.kundenserver.
mailer-daemon
variabel
noreply
-dav
law2
.sul.t-
.qmail@
t-ipconnect
t-dialin
ipt.aol
time
freeav
@ca.
abuse
winrar
domain.
host.
viren
bitdefender
spybot
detection
ewido.
emsisoft
linux
google
@foo.
winzip
@example.
bellcore.
@arin
mozilla
iana@
iana-
@iana
@avp
icrosoft.
@sophos
@panda
@kaspers
free-av
antivir
virus
verizon.
@ikarus.
@nai.
@messagelab
nlpmail01.
clock
 

The worm composes emails with both English and German texts. If the worm sends infected messages to domains with suffixes '.de', '.ch', '.at', '.li' and also to 'gmx.' domain, it composes messages in German, otherwise English messages are composed.

The worm composes the following messages:

Subjects:

Your Password & Account number
Ich habe Ihre email bekommen!
 

Body texts:

i've got an admin mail with a Password and Account info!
but the mail recipient are you! it's probably an esmtp error, i think.
i've copied the full mail text in the Windows text-editor & zipped.
ok, cya...
 

---- or ----

Hallo,
jemand schickt ihre privaten Mails auf meinem Account.
Ich schaetze mal, das es ein Fehler vom Provider ist.
Insgesamt waren es jetzt schon 6 Mails!
Ich habe alle Mail-Texte im Texteditor kopiert und gezippt.
Wenn es doch kein Fehler vom Provider ist, sorge dafuer das diese Dinger nicht mehr auf meinem Account
landen, es Nervt naemlich.
Gruss
 

Attachments:

MailTexte.zip
acc_text.zip