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  3. Trojan.Gimmiv.A

Trojan.Gimmiv.A

Risk Level 1: Very Low

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
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.
Writeup By: Elia Florio
Summary| Technical Details| Removal

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