Internet threat level: 1
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Email-Worm.Win32.Scano.e
| Detected | Apr 20 2006 21:33 GMT |
| Released | Apr 20 2006 21:33 GMT |
| Published | Apr 27 2006 11:14 GMT |
Removal instructions
Technical Details
This worm spreads via the Internet as an attachment to infected emails. It sends itself to email addresses harvested from the victim machine. The attachment to infected messages does not contain a copy of the worm, but an HTA component, which contains the worm's executable file.
The worm itself is a Windows PE EXE file approximately 18KB in size.
Installation
When installing, the worm copies itself to the Windows root directory as csrss.exe:
The worm then creates the following entries in the Windows system registry:
[HKLM\Software\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\explorer.exe]
"Debugger"="%Windir%\csrss.exe"
[HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "Application"="%Windir\csrss.exe"
Propagation via email
The worm harvests addresses from the MS Windows address books and also from files with the extensions listed below:
adb asp cfg cgi dbx dhtm dhtml eml htm html jsp mbx mdx mht mmf mra msg nch ods oft php pl sht shtm stm tbb txt uin wab wsh xls xml
The worm does not harvest addresses which contain the following strings:
0 2003 2004 2005 2006 --- .0 .00 .1 .2 .3 .4 .5 .6 .7 .8 .9 .gif .qmail @avp. @example. @foo @iana @messagelab @microsoft @subscribe abuse admin anyone@ bsd bugs@ cafee certific contract@ feste free-av f-secur gold-certs@ google help@ icrosoft info@ kasp linux listserv local Mailer-Daemon@ news nobody@ noone@ noreply ntivi panda pgp postmaster@ rating@ root@ samples sopho spam spm111@ support torvalds@ unix update winrar winzip
The worm attempts to establish a direct connection to the recipient's SMTP in order to send infected messages.
Infected messages
Examples:
Message subject
The message subject will be chosen at random from a list of 14 possible variants, all of which are in Russian.
Message body
The message body will be chosen at random from a list of 14 variants, all of which are in Russian.
Attachment name
The attachment does not contain a copy of the worm, but a polymorphic HTA component, which contains the worm's executable file. When the attached file is launched, it will create a file called ntldr.exe in the C:\ root directory, which will then be launched for execution. It is this file which is a copy of the worm.
Attachment name
The attachment name is chosen at random from a list of 9 variants, all of which are in Russian.
Payload
The worm connects to the following servers in order to download other files without the user's knowledge or consent:
http://207.**.250.119 http://84.**.161.192 http://85.249.**.35
Removal instructions
- Reboot the computer in Safe Mode (at the beginning of the boot sequence, press and hold F8, then choose Safe Mode from the Windows boot menu).
- Delete the following records from the system registry:
[HKLM\Software\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\explorer.exe]
"Debugger"="%Windir%\csrss.exe"[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
"Application"="%Windir\csrss.exe" - Delete the following files:
%Windir%\csrss.exe C:\ntldr.exe
- Reboot the computer as normal and check that you have deleted all infected messages from all mail folders.
- Update your antivirus databases and perform a full scan of the computer (download a trial version of Kaspersky Anti-Virus).
Email-Worms spread via email. The worm sends a copy of itself as an attachment to an email message or a link to its file on a network resource (e.g. a URL to an infected file on a compromised website or a hacker-owned website).
In the first case, the worm code activates when the infected attachment is opened (launched). In the second case, the code is activated when the link to the infected file is opened. In both case, the result is the same: the worm code is activated.
Email-Worms use a range of methods to send infected emails. The most common are:
- using a direct connection to a SMTP server using the email directory built into the worm’s code
- using MS Outlook services
- using Windows MAPI functions.
Email-Worms use a number of different sources to find email addresses to which infected emails will be sent:
- the address book in MS Outlook
- a WAB address database
- .txt files stored on the hard drive: the worm can identify which strings in text files are email addresses
- emails in the inbox (some Email-Worms even “reply” to emails found in the inbox)
Many Email-Worms use more than one of the sources listed above. There are also other sources of email addresses, such as address books associated with web-based email services.
Email-Worm.
- W32/Areses.
H. worm (Panda)
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