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Stoned.Standard

Risk Level 1: Very Low

Updated:
February 13, 2007 11:54:41 AM
Also Known As:
Deunis, Hawaii, Marijuana, New Zealand, San Diego, Smithsonian
Type:
Virus

The virus code is one sector in length and it reserves 4K of memory. Thus, on a 640K machine, CHKDSK would report 651,264 bytes of free memory.

On the hard drive, the original MBR is stored on physical sector 7 of the infected drive. The virus stores the original DOS boot sector in the physical sector at side 1, cylinder 0, sector 3 on infected floppy disks (logical sector 11). On 360K floppy disks, this is the last sector of the root directory. It overwrites the last 16 directory entries if the directory is completely full. On larger-capacity floppy disks, it is stored earlier in the root directory.

Upon booting from an infected disk, Stoned.Standard checks the MBR to see if it is infected. If it is not, the virus infects it. This is the only time the hard drive can be infected. If you remove the virus from the MBR while it is active in memory, the MBR is not re-infected. Also, on booting, there is a 1 in 8 chance the virus will beep and display its message.

The infected boot sector or MBR contains the plainly visible message:

      Your PC is now stoned! LEGALIZE MARIJUANA!
The message starts at offset 18Ah in the sector. By looking at the floppy boot or MBR sector with a disk editor, you can verify an infection. There is also a fairly common minor variant, which is detected by most anti-virus packages as being the same virus, in which the “LEGALIZE MARIJUANA” portion of the message has been corrupted.

Stoned.Standard was programmed by a University of Wellington student in New Zealand in 1987. By design, the virus infects MBRs and the boot sector of 360K disks. Under such conditions, the virus is relatively benign. However, the virus can damage data on any floppy disk it infects and the probability of damage increases as the capacity of the floppy disk increases. For example, on a 1.44 MB floppy disk, the virus overwrites entries 17-32 in the root.

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.
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