Discovered: September 11, 2002
Updated: February 13, 2007 11:40:27 AM
Also Known As: Trojan/Bounce [SecurityFocus], W32/Bounce
Type: Trojan Horse
Systems Affected: Windows
Trojan.IrcBounce is the detection for a collection of programs that a hacker can use to conceal intrusion and obtain administrator-level access to Microsoft Windows environments. These programs can be used to attack Windows environments that
- Have the default installation, in which the Administrator account has no password
- Use user names and passwords that are very common.
After it is installed into victim's system, it gives a remote attacker unobstructed access to the compromised computer.
NOTE : Definitions dated prior to September 11, 2002, may detect some components of this threat as IRC Trojan or IRC.Mimic.
Please see the following Microsoft Knowledge Base article for additional information:
Antivirus Protection Dates
- Initial Rapid Release version September 12, 2002
- Latest Rapid Release version November 04, 2019 revision 019
- Initial Daily Certified version September 12, 2002
- Latest Daily Certified version November 04, 2019 revision 065
- Initial Weekly Certified release date September 18, 2002
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
This Trojan consists of the following programs, all of which are detected as Trojan.IrcBounce by Symantec antivirus products:
This Trojan also uses the following clean programs, which are not detected by Symantec antivirus products:
Taskmngr.exe is actually Mirc32.exe version 5.7. The Trojan uses this file to run all of its mIRC scripts, including Dll32.hlp, Dll32NT.hlp, Xvpll.hlp, Httpsearch.ini, and NT32.ini.
The Trojan uses its scripts to attempt to obtain administrator-level access to remote Microsoft Windows environments that
- Have the default installation, in which the Administrator account has no password
- Use user names and passwords that are very common
If the threat gets the control of a remote system, it installs all of its components. This is how the Trojan spreads itself.
The Trojan allows the hacker to remotely take control over the compromised computer. This can include:
- Distributed Denial of Service(DDoS)
- Repeated opening of a TCP port
- Full control over the file system
- Uploading to and downloading from the host computer
- Running files of the hacker's choice
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.
NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
- Update the virus definitions.
- Run a full system scan, and delete all files that are detected as Trojan.IrcBounce.
NOTE: If, after you delete Trojan.IrcBounce, the mIRC program starts each time that you start Windows, then delete from the registry \Run key the value that refers to Taskmngr.exe.
For details on how to do this, read the following instructions.
To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:
- Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
- Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.
Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.
To scan for and delete the infected files:
- Start your Symantec antivirus program, and make sure that it is configured to scan all files.
- Norton AntiVirus consumer products: Read the document How to configure Norton AntiVirus to scan all files.
- Symantec enterprise antivirus products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
- Run a full system scan.
- If any files are detected as infected with Trojan.IrcBounce, click Delete.
To delete from the registry the value that refers to Taskmngr.exe:
As noted in the Technical Description, the Trojan uses Taskmngr.exe, which is actually a renamed copy of the legitimate program Mirc32.exe. Because it is a legitimate program, it is not detected by Symantec antivirus products. The Trojan may add a reference to this file to a registry key so that mIRC starts each time that you start Windows. This is not harmful, but can be annoying. Follow these steps to remove the reference from the registry:
CAUTION : Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.
- Click Start, and click Run. The Run dialog box appears.
- Type regedit and then click OK. The Registry Editor opens.
- Navigate to the key
- In the right pane, look for a value or value data that refers to
- Delete the reference if you find it.
- Exit the Registry Editor.
Writeup By: Yana Liu