Sober.J worm was seeded in e-mails on 31st of January 2005. It is quite similar to the previous variants.
Disinfection & Removal
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] "<random>" = "%WinSysDir%\<random>.exe" [HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "<random>" = "%WinSysDir%\<random>.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:
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:
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:
I've got YOUR email on my account!!
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
The ZIP archive sent by the worm contains the worm's executable file with the following name:
mail_text-info.txt <lots of spaces> .pif
The worm does not use any exploits to start its file automatically on a recipient's system.
The worm does not infect a computer if the file with the 'stopruns.zhz' name is found in Windows System folder.
Sober.J worm is detected with the following FSAV updates:
Detection Type: PC
Description Created: Alexey Podrezov; January 31st, 2005
Description Last Modified: Alexey Podrezov; February 21st, 2005