Threat description



Sober.L worm was seeded in e-mails 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 e-mail messages with English or German texts.


Automatic action

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You may also refer to the Knowledge Base on the F-Secure Community site for more information.

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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 '' file to Windows folder.

Spreading in E-mails

The worm sends different types of e-mail 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 e-mail 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 e-mail 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  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 e-mails 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:


Your Password & Account number  Ich habe Ihre E-Mail 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   


Sober.L worm is detected with the following FSAV updates:

Detection Type: PC

Database: 2005-03-07_06

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