Risk Level 1: Very Low

Discovered: September 22, 2010
Updated: September 23, 2010 6:29:13 AM
Type: Trojan
Infection Length: Varies
Systems Affected: Windows 98, Windows 95, Windows XP, Windows Me, Windows Vista, Windows NT, Windows Server 2003, Windows 2000


Backdoor.Locobad is a Trojan horse that downloads files and opens a back door on the compromised computer.

Antivirus Protection Dates

  • Initial Rapid Release version September 22, 2010 revision 006
  • Latest Rapid Release version September 22, 2010 revision 018
  • Initial Daily Certified version September 22, 2010 revision 009
  • Latest Daily Certified version September 22, 2010 revision 009
  • Initial Weekly Certified release date September 29, 2010

Threat Assessment


  • Wild Level: Low
  • Number of Infections: 0 - 49
  • Number of Sites: 0 - 2
  • Geographical Distribution: Low
  • Threat Containment: Easy
  • Removal: Easy


  • Damage Level: Medium
  • Payload: May open a back door
  • Compromises Security Settings: Lowers Internet security settings


  • Distribution Level: Low


The Trojan may be dropped on to the computer by other malware.

When executed, the Trojan copies itself as the following file:
%UserProfile%/Local Settings/Temp/[EXISTING EXECUTABLE FILE NAME 1].exe

It may also copy the original dropper as the following file:
%UserProfile%/Local Settings/[EXISTING EXECUTABLE FILE NAME 2].exe

Note: [EXISTING EXECUTABLE FILE NAME 1] and [EXISTING EXECUTABLE FILE NAME 2] denote the names of executable files that exist on the compromised computer. Examples include the following executable file names:
  • crss.exe
  • taskmgr.exe
  • smss.exe
  • sched.exe

The Trojan creates the following file so that it runs every time Windows starts:
%UserProfile%/Start Menu/Programs/Startup/[EXISTING EXECUTABLE FILE NAME 1].lnk

It then creates the following registry entry so that it runs every time Windows starts:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\run\"[EXISTING PROGRAM NAME]" = "%UserProfile%\Local Settings\temp\[EXISTING EXECUTABLE FILE NAME 1].exe"

Note: [EXISTING PROGRAM NAME] denotes the name of an existing program. Examples include the following names:
  • Reader
  • Proxy1

The Trojan then modifies the following registry entries to alter Internet security settings:
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\"WarnonZoneCrossing" = "0"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\"WarnOnPostRedirect" = "0"

The Trojan attempts to connect to one or more of the following URLs:
  • [http://][NETWORK ADDRESS]/brows[REMOVED]
  • [http://][NETWORK ADDRESS]/login_[REMOVED]
  • [http://][NETWORK ADDRESS]/login_[REMOVED]
  • [http://][NETWORK ADDRESS]/mainlogi[REMOVED]
  • [http://][NETWORK ADDRESS]/mainlogi[REMOVED]
  • [http://][NETWORK ADDRESS]/quer[REMOVED]
  • [http://][NETWORK ADDRESS]/quer[REMOVED]
  • [http://][NETWORK ADDRESS]/searc[REMOVED]
  • [http://][NETWORK ADDRESS]/searc[REMOVED]
  • [http://][NETWORK ADDRESS]/userfo[REMOVED]
  • [http://][NETWORK ADDRESS]/userfo[REMOVED]
  • [http://][NETWORK ADDRESS]/webfo[REMOVED]

Where [NETWORK ADDRESS] is one of the following:
  • biz-center.51vip.biz
  • bt-dns.imblog.in
  • centralmall.8866.org
  • facebook.imzone.in
  • netdns.008.net
  • registercenter.vicp.cc
  • search.vipbookonline.com
  • tradeforum.2288.org
  • vipcenter.8866.org
  • vip-pictures.008.net
  • vipuser.iphosts.org
  • webfive.8866.org
  • webmail2k.9966.org
  • www.update.10dig.net

The Trojan periodically downloads files that may be executed on the compromised computer.


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.