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W32.Wergimog

Risk Level 1: Very Low

Discovered:
March 12, 2012
Updated:
March 13, 2012 7:51:33 AM
Type:
Worm
Systems Affected:
Windows 2000, Windows 7, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows Server 2008, Windows Vista, Windows XP
When the worm is executed, it copies itself as one of the following files:
  • %System%\service[RANDOM NUMBER].exe
  • %Windir%\service[RANDOM NUMBER].exe

Next, the worm may create the following registry entries, so that it executes whenever Windows starts:
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"Adobe Reader Speed Launcher" = "%System%\service[RANDOM NUMBER].exe"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\"Adobe Reader Speed Launcher" = "%System%\service[RANDOM NUMBER].exe"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Adobe Reader Speed Launcher" = "%System%\service[RANDOM NUMBER].exe"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"Adobe Reader Speed Launcher" = "%Windir%\service[RANDOM NUMBER].exe"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\"Adobe Reader Speed Launcher" = "%Windir%\service[RANDOM NUMBER].exe"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Adobe Reader Speed Launcher" = "%Windir%\service[RANDOM NUMBER].exe"

It may also create the following registry entry:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\pPkzmsiesk\"ISkxnksnam" = "[RANDOM VALUE]"

Next, it creates the following mutex so that only one instance of the threat executes on the computer:
kkk

It starts the Explorer.exe process and injects its code into it.

It then attempts to open a back door by connecting to the following remote location on TCP port 2040 or 80:
v2z.imageshak.biz

It may then perform the following actions:
  • Download and execute a remote file
  • Perform UDP and SYN flood attacks
  • List the directory
  • Send the user name of the compromised computer
  • Delete itself
  • Capture packets
  • Open a requested URL

It attempts to steal host, user, port, and password information stored in the following files:
  • %ProgramFiles%\FileZilla\sitemanager.xml
  • %ProgramFiles%\FileZilla\recentservers.xml

It also attempts to steal the following information related to Mozilla Firefox:
  • Current version
  • Main page
  • Installation directory
  • All information in the Firefox SQLite database

The worm spreads by copying itself to removable drives as the following file:
%DriveLetter%\RECYCLER\autorun.exe

It may also create the following file in order to execute whenever the drive is used on another computer:
%DriveLetter%\autorun.inf

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: Hiroshi Shinotsuka
Summary| Technical Details| Removal

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