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Malicious Software Encyclopedia: WinNT/Ispro

Published: July 12, 2005

WinNT/Ispro is a family of kernel-mode rootkit programs that targets computers running certain versions of Microsoft Windows. This rootkit is often bundled with adware that has also infected the computer. The rootkit allows an attacker to prevent deletion or modification of certain files and registry keys on an infected computer.

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Glossary Terms

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Trojan horse

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worm

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On This Page
Threat OverviewThreat Overview
Technical AnalysisTechnical Analysis
How to Prevent InfectionHow to Prevent Infection
How to Tell If Your Computer Is InfectedHow to Tell If Your Computer Is Infected
How to Recover from InfectionHow to Recover from Infection

Threat Overview

Class/typeTrojan - Rootkit-Stealth
DiscoveredFebruary 16, 2005
CirculatingYes
Affected operating systemsWindows 2000
Windows XP
Windows Server 2003
Affected software Not specified
Infection ratingLow
Recovery difficultyModerate
Damage ratingMedium
Transmission ratingLow

Technical Analysis

When WinNT/Ispro runs, it interferes with the operation of certain Windows operating system APIs. It uses a configuration file, %windir%\delprot.ini, to specify file names and registry keys that cannot be deleted. It also prevents modification or deletion of %windir%\delprot.ini and all the files in the folder %windir%\isrvs. It keeps a history in %windir%\delprot.log of attempts to remove or modify the protected registry keys and files.

How to Prevent Infection

Take the following steps to help prevent infection on your system:
  • Enable a firewall on your computer.
  • Get the latest computer updates.
  • Use up-to-date antivirus software.
  • Use caution with unknown attachments.
  • Do not respond to requests for personal information via e-mail or IM.
  • Remove unneeded network shares.
  • Use strong passwords.

Enable a firewall on your computer

Use a third-party firewall product or turn on the Microsoft Windows XP Internet Connection Firewall.
To turn on the Internet Connection Firewall in Windows XP
  1. Click Start, and click Control Panel.
  2. Click Network and Internet Connections, and click Network Connections. If you do not see Network and Internet Connections, click Switch to Category View.
  3. Highlight a connection that you want to help protect, and click Change settings of this connection.
  4. Click Advanced, and select Protect my computer and network by limiting or preventing access to this computer from the Internet.
  5. Click OK.

Get the latest computer updates

Updates help protect your computer from viruses, worms, and other threats as they are discovered. You can use the Automatic Updates feature in Microsoft Windows XP to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
To turn on Automatic Updates in Windows XP
  1. Click Start, and click Control Panel. 
  2. Click Performance and Maintenance. If you do not see Performance and Maintenance, click Switch to Category View.
  3. Click System.
  4. Click Automatic Updates, and select Keep my computer up to date.
  5. Select a setting. Microsoft recommends selecting Automatically download the updates, and install them on the schedule that I specify and setting a regular update time.
  6. If you choose to have Automatic Updates notify you in step 5, you will see a notification balloon when new downloads are available to install. Click the notification balloon to review and install updates.

Use up-to-date antivirus software

Most antivirus software can detect and prevent infection by known malicious software. You should always run antivirus software on your computer that is updated with the latest signature files to automatically help protect you from infection. If you don't have antivirus software installed, you can get it from one of several companies. For more information, see http://www.microsoft.com/athome/security/downloads/default.mspx

Use caution with unknown attachments

Use caution before opening unknown e-mail or IM attachments, even if you know the sender. If you cannot confirm with the sender that a message is valid and that an attachment is safe, delete the message immediately, and run up-to-date antivirus software to check your computer for viruses.

Do not respond to requests for personal information via e-mail or IM

Microsoft and most legitimate businesses will never ask for passwords, credit card numbers, or other personal information in an e-mail or instant message. If you do receive a message requesting this kind of information, don't respond. If you think the message is legitimate, contact the company by phone or through their Web site to confirm.

Remove unneeded network shares

Malicious software can often spread over network shares. Remove unneeded network shares that are mapped to your computer.
To remove network shares in Windows XP
  1. On the Start menu, click My Computer.
  2. On the Tools menu, click Disconnect Network Drives…
  3. In the Disconnect Network Drives dialog box, click the drives to disconnect and click OK.

Use strong passwords

A strong password has at least eight characters and includes a combination of letters, numbers, and symbols. It is easy for you to remember, but difficult for others to guess. Weak passwords include any words in the dictionary, names, dates, consecutive letters or numbers, common words with symbol substitutions (for example, p@ssw0rd), and so on.

How to Tell If Your Computer Is Infected

WinNT/Ispro is often bundled with adware that has also infected the computer. The Trojan attempts to hide any signs that it is on a computer. However, it may cause unusual behavior, performance degradation, or system crashes.

How to Recover from Infection

Automatic Recovery
To attempt to automatically remove this threat, run one of the following removal tools:

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