Infection Length: 40,179 bytes
Systems Affected: Windows XP, Windows Server 2003, Windows 2000
Wild Level: Low
Removal: Easy
Damage Level: Medium
Payload: Opens a back door on the compromised computer.
Backdoor.Bifrose.M is a Trojan horse that opens a back door on the compromised computer.
Once executed, the Trojan creates the following file:
%System32%\msnmsie.exe
Next, the Trojan creates the following registry entry so that it runs every time Windows starts:
HKEY_CURRENT_USER\software\Microsoft\Windows\CurrentVersion\Run\"StartKey" = "%System%\msnmsie.exe"
It also creates the following registry subkeys:
* HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A5CDF7EC-751B-46aa-AD69-4005FE080DE8}
* HKEY_LOCAL_MACHINE\SOFTWARE\SKav
* HKEY_CURRENT_USER\Software\SKav
The Trojan then creates the following registry entries:
* HKEY_LOCAL_MACHINE\SOFTWARE\SKav\"nck" = "99 6F D5 66 A0 AC EA 5F F7 EC 7F 84 DC 8A DA 00 A8 5F E4 52 A0 AC EA 5F F7 EC 7F 84 DC 8A DA 00"
* HKEY_CURRENT_USER\Software\SKav\"klg" = "00"
* HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A5CDF7EC-751B-46aa-AD69-4005FE080DE8}\"stubpath" = "C:\WINDOWS\system32\msnmsie.exe s"
It creates a new Internet Explorer instance and injects itself into this process to hide its presence on the compromised computer.
It periodically attempts to access the following Web sites:
* freexuite.ns01.us
* gundamms08.ns1.name
The Trojan may open a back door allowing a remote attacker unauthorized access on the compromised computer.
TECHNICAL DETAILS
We encourages all users and administrators to adhere to the following basic security "best practices":
* Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
* If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
* 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.
* Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
* Isolate infected computers quickly to prevent further compromising your organization. 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.
* Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
* If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
* 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.
* Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
* Isolate infected computers quickly to prevent further compromising your organization. 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.
REMOVAL
1. Disable System Restore (Windows Me/XP).
2. Update the virus definitions.
3. Run a full system scan.
4. Delete any values added to the registry.
To delete the value from the registry
Important: We strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified subkeys only.
1. Click Start > Run.
2. Type regedit
3. Click OK.
4. Navigate to and delete the following registry entries:
* HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"StartKey" = "%System%\msnmsie.exe"
* HKEY_LOCAL_MACHINE\SOFTWARE\SKav\"nck" = "99 6F D5 66 A0 AC EA 5F F7 EC 7F 84 DC 8A DA 00 A8 5F E4 52 A0 AC EA 5F F7 EC 7F 84 DC 8A DA 00"
* HKEY_CURRENT_USER\Software\SKav\"klg" = "00"
* HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A5CDF7EC-751B-46aa-AD69-4005FE080DE8}\"stubpath" = "C:\WINDOWS\system32\msnmsie.exe s"
5. Navigate to and delete the following registry subkeys:
* HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A5CDF7EC-751B-46aa-AD69-4005FE080DE8}
* HKEY_LOCAL_MACHINE\SOFTWARE\SKav
* HKEY_CURRENT_USER\SOFTWARE\SKav
6. Exit the Registry Editor.
Note: If the risk creates or modifies registry subkeys or entries under HKEY_CURRENT_USER, it is possible that it created them for every user on the compromised computer. To ensure that all registry subkeys or entries are removed or restored, log on using each user account and check for any HKEY_CURRENT_USER items listed above.
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