1. Symantec/
  2. Security Response/
  3. Trojan.Spamnost


Risk Level 1: Very Low

December 19, 2011
April 15, 2013 1:24:47 AM
Also Known As:
Troj/Nost-A [Sophos], Troj/Zbot-EON [Sophos]
Systems Affected:
When the Trojan is executed, it copies itself as the following file:
%UserProfile%\Application Data\[RANDOM CHARACTERS]\svcnost.exe

The Trojan then creates the following registry entry so that it runs every time Windows starts:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"mssend" = "\"%UserProfile%\Application Data\[RANDOM CHARACTERS]\svcnost.exe\""

Next, the Trojan creates the following registry entries to bypass the Windows Firewall policy for unrestricted Internet access:
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List\"%UserProfile%\Application Data\[RANDOM CHARACTERS]\svcnost.exe" = "%UserProfile%\Application Data\[RANDOM CHARACTERS]\svcnost.exe:*:Enabled:ldrsoft"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List\"%UserProfile%\Application Data\[RANDOM CHARACTERS]\svcnost.exe" = "%UserProfile%\Application Data\[RANDOM CHARACTERS]\svcnost.exe:*:Enabled:ldrsoft"

The threat then creates the following registry entry to alter Internet Explorer settings:
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\LowRegistry\"SavedLegacySettingsML" = "[BINARY DATA]"

The Trojan then exectues from the new location, closes the original executabe, and then creates the following file, which is a SSL .dll file used for encrypting communication with the remote attacker server:
%UserProfile%\Application Data\desktop.ini

It may also create the following .dll file, which is used to compress and decompress data over the communication channel:
%UserProfile%\Application Data\ntuser.dat

It then accesses the following URLs in an attempt to obtain new configuration parameters to use for spamming:
  • [http://][REMOVED]
  • [http://][REMOVED]
  • [http://][REMOVED]
  • [http://][REMOVED]
  • [http://][REMOVED]

The Trojan contains the following predetermined spam email components, which it emails to predetermined addresses:

(One of the following)
  • Christmas SALE 30%: get freee zithromax prf0essional suuper
  • Christmas SALE 30%: if you have difficulties in xxxSex - buu
  • Christmas SALE 30%: Vaigr@ pr0fessoinal - 1mp0tTence defense
  • Christmas SALE 30%: Viarg@ superr @ctive - a drugg for seks
  • Christmas SALE 30%: Viegra professionnal - where did you get
  • Christmas SALE 30%: Viegra superr aactive - finish off with
  • Christmas SALE 30%: Vig@ra profess1oonal - imphotence defens
  • Christmas SALE 30%: Waigra suuper activve - a druUg for Sexx
  • Christmas SALE 30%: Wi@gar pr0fessinoal - iimpotence defense
  • Christmas SALE 30%: Wiara professio@nl - 1mp0tence defense
  • Christmas SALE 30%: Wiara profses1onal - be on the way to se
  • Christmas SALE 30%: Wiarg@ pr0feessional - immpotence defens
  • Christmas SALE 30%: Wiarga profesionnal - immp0tence defense
  • Christmas SALE 30%: Wig@ra ssuper acctive - a durg for sexX
  • Christmas SALE 30%: Wigar@ suuper act1ve - a dDrug for seXx
  • Christmas SALE 30%: Wigra porfessi0nal - 1mp0etnce defense
  • Christmas SALE 30%: Wiiagra profess1onaal - 1mph0tence defen
  • Christmas SALE 30%: your erectoin under the influence of Vi@
  • Christmas SALE 30%: your errection under the influence of Vi

Message Body:
Hello darling
next he disarm sharply chilly
your ereEctiOon under the influence of V
Dasia Blakemore

The email address that will appear as though it comes from the happymedic.com domain. An example of a used sender is:
"Dr Blakemore" <betsy475-geyer@happymedic.com>

The Trojan may download further emails spam messages.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.
Writeup By: Branko Spasojevic
Summary| Technical Details| Removal

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