Threat Description

Sober.J

Details

Aliases: Sober.J, W32/Sober.J@mm, Email-Worm.Win32.Sober.j, W32/Reblin.A@mm, Email-Worm.Win32.VB.af
Category: Malware
Type:
Platform: W32

Summary


Sober.J worm was seeded in e-mails on 31st of January 2005. It is quite similar to the previous variants.



Removal


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

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



Technical Details


The worm is written in Visual Basic. The worm's file is a UPX packed PE executable about 43 kilobytes long. The unpacked worm's file size is over 140 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:

Then the worm installs itself to system. It copies itself to Windows System folder with a semi-randomly generated name and EXE extension. The following text strings are used to generate the file name of the worm's executable:

sys  host  dir  expoler  win  run  log  32  disc  crypt  data  diag  spool  service  smss32   

After that the worm creates startup keys for its file in Windows Registry. The key names are also semi-randomly generated from the above given list. The following keys are created:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Run]  "" = "%WinSysDir%\.exe"  [HKLM\Software\Microsoft\Windows\CurrentVersion\Run]  "" = "%WinSysDir%\.exe"   

During its installation cycle the worm creates the following files in Windows System folder:

dgssxy.yoi  sysmms32.lla  cvqaikxt.apk  Odin-Anon.Ger  nonrunso.ber   

These files have zero length and they are used to disable previous variants of Sober if they are installed on an infected computer.

Additionally the worm creates the following files:

dgsfzipp.gmx  datamx.dam   

The 'dgsfzipp.gmx' file is a MIME-encoded ZIP archive with the worm's file. This file will be used for spreading of the worm in e-mail messages. The 'datamx.dam' file contains e-mail addresses collected by the worm on an infected computer.

Additionally the worm creates the 'read.me' file that contains the following text:

Ist nur eine kleine Test-Version  In diesem Sinne:  Odin alias Anon   
Spreading in e-mails

The worm sends e-mail messages with English and German texts and its file attached. The attachment is a ZIP archive containing the worm's executable. The worm composes two different e-mail messages. Here's an example of an English message sent by the worm:

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 found e-mail addresses and user names are saved in the file that the worm creates in Windows System folder:

datamx.dam   

When the worm is active in memory it blocks access to these files as well as to its MIME-encoded files and its executable file.

The worm ignores e-mail addresses that contain any of the following substrings:

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

If the worm sends infected messages to domains with suffixes '.de', '.ch', '.at', it composes a message in German, otherwise English message is composed.

The worm composes the following English message:

Subject:

I've got YOUR email on my account!!   

Body:

Hello,  First, Sorry for my very bad English!  Someone send your private mails on my email account!  I think it's an Mail-Provider or SMTP error.  Normally, I delete such emails immediately, but in the mail-text  is a name & adress. I think it's your name and adress.  The sender of this mails is in the text file, too.  In the last 8 days i've got 7 mails in my mail-box, but the  recipient are you, not me. lol  OK, I've copied all email text in the Windows Text-Editor and  i've zipped the text file with WinZip.  bye   

Attachment:

email_text.zip   

or

text.zip   

The ZIP archive sent by the worm contains the worm's executable file with the following name:

mail_text-info.txt     .pif   

The worm does not use any exploits to start its file automatically on a recipient's system.

Deactivation

The worm does not infect a computer if the file with the 'stopruns.zhz' name is found in Windows System folder.



Detection


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

Detection Type: PC
Database: 2005-01-31_01



Description Details: Alexey Podrezov; January 31st, 2005
Description Last Modified: Alexey Podrezov; February 21st, 2005


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