Trojan.Gimmiv.A

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Discovered: October 24, 2008
Updated: October 29, 2008 3:48:55 PM
Also Known As: Troj/Gimmiv-A [Sophos], Trojan-Spy:W32/Gimmiv.A [F-Secure], Win32/Gimmiv.A [Computer Associates], Gimmiv.A [Panda Software], Win32/Gimmiv.B [Computer Associates], Spy-Agent.da [McAfee], WORM_GIMMIV.A [Trend], Troj/Gimmiv-Gen [Sophos]
Type: Trojan
Infection Length: 397,312 bytes
Systems Affected: Windows
CVE References: CVE-2006-3439 | CVE-2008-4250

Trojan.Gimmiv.A is a Trojan horse that opens a back door, attempts to exploit remote vulnerabilities, and may steal information from the compromised computer.

Note: Definitions before October 24, 2008 may detect this threat as Infostealer .


Technical Description

The Trojan arrives and is downloaded and installed through the Microsoft Windows Server Service RPC Handling Remote Code Execution Vulnerability (BID 31874 ) from the following remote host:

  • [http://]59.106.145.58/n1.[REMOVED]
  • [http://]59.106.145.58/n2.[REMOVED]
  • [http://]59.106.145.58/n3.[REMOVED]
  • [http://]59.106.145.58/n4.[REMOVED]
  • [http://]59.106.145.58/n5.[REMOVED]
  • [http://]59.106.145.58/n6.[REMOVED]
  • [http://]59.106.145.58/n7.[REMOVED]
  • [http://]59.106.145.58/n8.[REMOVED]
  • [http://]59.106.145.58/n9.[REMOVED]


When executed, it drops the following file:
%System%\wbem\sysmgr.dll

Next, it registers the file sysmgr.dll as a service by adding entries to the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\sysmgr

The service is configured with the following characteristics and will run when Windows starts:
Display Name: System Maintenance Service
Image Path: %SystemDrive%\System32\svchost.exe -k sysmgr
Object Name: LocalSystem
Startup Type: Automatic

It also creates the following registry entry:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost\"sysmgr" = "sysmgr"

Once the System Maintenance Service is started, the Trojan deletes the main installer file n[X].exe using the %Temp%\[RANDOM FILE NAME].BAT file

Note : [X] represents a number from 1 through 9.

Next, it sends an ICMP PING packet to the following remote hosts:
  • 202.108.22.44
  • 64.233.189.147


Note:
The ICMP packet sent out contains the following string:
abcde12345fghij6789

Next, it checks for the presence of the following registry subkeys on the compromised computer:
  • HKEY_LOCAL_MACHINE\SOFTWARE\BitDefender
  • HKEY_LOCAL_MACHINE\SOFTWARE\KasperskyLab
  • HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\PatchInst\NIS
  • HKEY_LOCAL_MACHINE\SOFTWARE\TrendMicro
  • HKEY_LOCAL_MACHINE\SOFTWARE\Kingsoft
  • HKEY_LOCAL_MACHINE\SOFTWARE\rising
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\OneCare Protection
  • HKEY_LOCAL_MACHINE\SOFTWARE\Jiangmin


It also checks for the presence of the following processes active on the compromised computer:
  • avp
  • avp.exe


Next the Trojan starts gathering information and configuration data, including the following information:
  • Username
  • Computer name
  • Network info such as: ie. IP address, and MAC address
  • Outlook Express Credential Information
  • Windows Protected Storage Passwords and Credentials
  • Installed components under HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID registry subkeys
  • Installed Microsoft patches


The information is encrypted and posted over HTTP to the following host:
[http://]59.106.145.58/test[REMOVED] = [NUM1]&?def = [NUM2]

Note: [NUM1] is a number indicating the software detected on the compromised computer:
  • 1 = Kaspersky
  • 2 = No antivirus
  • 3 = Symantec NIS
  • 4 = TrendMicro
  • 5 = Kingsoft
  • 6 = Rising
  • 7 = Microsoft OneCare
  • 8 = Jiangmin
  • 9 = BitDefender


[NUM2] is a number indicating the operating system used on the compromised computer:
  • 1 = Windows 2000
  • 2 = Windows XP
  • 3 = Windows Vista
  • 4 = Windows 2003
  • 5 = Not found


The Trojan may also scan for recently used and opened file links by searching the following registry subkey:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders\Recent

The Trojan then opens a back door on the compromised computer which may allow for the following actions:
  • Download and execute remote files
  • Send machine configuration data to a remote host using HTTP
  • Steal information
  • Uninstall and delete itself


Note: If the Trojan does not successfully download the remote files, it will not have the capability to spread over the local network. At the time of writing, the remote host that is contacted by the Trojan is no longer available and no further downloaded code has been observed.

It may download the following file from a remote server:
%CurrentFolder%\inetproc02x.cab

If the above file is downloaded successfully, the Trojan creates and executes the following files:
%System%\wbem\basesvc.dll (Bloodhound.Exploit.212 )
%System%\wbem\syicon.dll (Trojan Horse )
%System%\wbem\winbase.dll
%System%\wbem\install.bat
%System%\wbem\winbaseinst.exe

It then deletes the following files:
%System%\wbem\install.bat
%System%\wbem\winbaseinst.exe

The Trojan then creates a new service with the following characteristics:
Display Name: Windows NT Baseline
Image Path: %SystemDrive%\System32\svchost.exe -k winbase.dll
Object Name: Local System
Startup Type: Automatic

It also creates the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BaseSvc\Parameters\"ServiceDll" = "%System%\winbase.dll"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BaseSvc\Parameters\"ServiceMain" = "ServiceMainFunc"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost\"BaseSvc" = "BaseSvc"

The Trojan may try to contact the following domains:
  • [http://]summertime.1gokurimu.com/icon[REMOVED]
  • [http://]perlbody.t35.com/icon[REMOVED]
  • [http://]doradora.atzend.com/icon[REMOVED]


The basesvc.dll file is registered and executed as a system service that scans the local network by sending ARP packets to randomly generated IP addresses.

The file then attempts to exploit the following vulnerabilities on computers identified during the scan:
  • Microsoft Windows Server Service RPC Handling Remote Code Execution Vulnerability (BID 31874)
  • Microsoft Windows Server Service Remote Buffer Overflow Vulnerability (BID 19409)


Next, any computers that have been compromised by either of the above exploits may attempt to download a malicious file from the following remote location:
[http://]59.106.145.58

Recommendations

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.


Removal

Before you begin:
This risk takes advantage of known Microsoft Windows vulnerabilities. To prevent re-infection, you must apply the appropriate patches. If you are running Windows NT/2000/XP, make sure that you have patched the following:

  • Microsoft Windows Server Service Remote Buffer Overflow Vulnerability (BID 19409)
  • Microsoft Windows Server Service RPC Handling Remote Code Execution Vulnerability (BID 31874)
The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
  1. Disable System Restore (Windows Me/XP).
  2. Update the virus definitions.
  3. Find and stop the service.
  4. Run a full system scan.
  5. Delete any values added to the registry.

For specific details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, reenable System Restore by following the instructions in the aforementioned documents.

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article: Antivirus Tools Cannot Clean Infected Files in the _Restore Folder (Article ID: Q263455).

2. To update the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain virus definitions.

    If you use Norton AntiVirus 2006, Symantec AntiVirus Corporate Edition 10.0, or newer products, LiveUpdate definitions are updated daily. These products include newer technology.

    If you use Norton AntiVirus 2005, Symantec AntiVirus Corporate Edition 9.0, or earlier products, LiveUpdate definitions are updated weekly. The exception is major outbreaks, when definitions are updated more often.


  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted daily. You should download the definitions from the Symantec Security Response Web site and manually install them.

The latest Intelligent Updater virus definitions can be obtained here: Intelligent Updater virus definitions . For detailed instructions read the document: How to update virus definition files using the Intelligent Updater .

3. To find and stop the service
  1. Click Start > Run.
  2. Type services.msc, and then click OK.
  3. Locate and select the service that was detected.
  4. Click Action > Properties.
  5. Click Stop.
  6. Change Startup Type to Manual.
  7. Click OK and close the Services window.
  8. Restart the computer.

4. To run a full system scan
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.

    For Norton AntiVirus consumer products: Read the document: How to configure Norton AntiVirus to scan all files.

    For Symantec AntiVirus Enterprise products: Read the document: How to verify that a Symantec Corporate antivirus product is set to scan all files.


  2. Run a full system scan.
  3. If any files are detected, follow the instructions displayed by your antivirus program.
Important: If you are unable to start your Symantec antivirus product or the product reports that it cannot delete a detected file, you may need to stop the risk from running in order to remove it. To do this, run the scan in Safe mode. For instructions, read the document, How to start the computer in Safe Mode . Once you have restarted in Safe mode, run the scan again.


After the files are deleted, restart the computer in Normal mode and proceed with the next section.

Warning messages may be displayed when the computer is restarted, since the threat may not be fully removed at this point. You can ignore these messages and click OK. These messages will not appear when the computer is restarted after the removal instructions have been fully completed. The messages displayed may be similar to the following:

Title: [FILE PATH]
Message body: Windows cannot find [FILE NAME]. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search.

5. To delete the value from the registry
Important: Symantec 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. For instructions refer to the document: How to make a backup of the Windows registry .
  1. Click Start > Run.
  2. Type regedit
  3. Click OK.

    Note: If the registry editor fails to open the threat may have modified the registry to prevent access to the registry editor. Security Response has developed a tool to resolve this problem. Download and run this tool, and then continue with the removal.

  4. Navigate to and delete the following registry entries:

    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost\"sysmgr" = "sysmgr"
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BaseSvc\Parameters\"ServiceDll" = "%System%\winbase.dll"
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BaseSvc\Parameters\"ServiceMain" = "ServiceMainFunc"
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost\"BaseSvc" = "BaseSvc"


  5. Navigate to and delete the following registry subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\sysmgr

  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.

Writeup By: Elia Florio