F-Secure
Tools
Backdoor:W32/IRCBot.BNS
| Name : | Backdoor:W32/IRCBot.BNS |
| Category: | Malware |
| Type: | Backdoor |
| Platform: | W32 |
Summary
IRCBot represents a large family of backdoors - remote access tools used by hackers.
These tools allow for the control of a victim's computer remotely by sending specific commands via IRC channels. Also, these backdoors can steal data and spread to computers vulnerable to exploits.
These tools allow for the control of a victim's computer remotely by sending specific commands via IRC channels. Also, these backdoors can steal data and spread to computers vulnerable to exploits.
Disinfection
Automatic Disinfection
Usually standalone malware (backdoors, worms, trojans, etc.) is automatically removed by F-Secure Anti-Virus (FSAV) starting from version 5.40. Malware files get automatically renamed by FSAV, so they can not be started any more. In some rare cases, when automatic disinfection is not possible, a user can select disinfection action by him/herself to make FSAV rename or delete an infected file. In some special cases it is recommended to use specific disinfection tools provided by F-Secure. They can be downloaded from our ftp site:
ftp://ftp.f-secure.com/anti-virus/tools/
F-Secure Anti-Virus can be purchased from our webshop or from our authorised distributors. A trial version F-Secure Anti-Virus, limited to 30 days, can be downloaded from our website:
http://www.f-secure.com/download-purchase/
All the latest versions of FSAV can download anti-virus database updates automatically. However, these updates can be also downloaded and installed manually from our web or ftp sites:
http://www.f-secure.com/download-purchase/updates.shtml
Manual Disinfection
To manually disinfect standalone malware (backdoors, worms, trojans, etc.) it's usually enough to delete all infected files from a computer and to restart it. Active malware files are usually locked by operating system so different disinfection approaches are required for different operating systems.
Please note that manual disinfection is a risky process, so it is recommended only for advanced users.
If Windows 95, 98 and ME operating system is used, it is recommended to restart a computer from a bootable system diskette and to delete an infected file from command prompt. For example if a malicious file named ABC.EXE is located in Windows folder, it is usually enough to type the following command at command prompt:
DEL C:\WINDOWS\ABC.EXE
and to press Enter. After that an infected file will be gone. If Windows NT, 2000 or XP is used, a malicious file has to be renamed with a different extension (for example .VIR) and then a system has to be restarted. After restart a renamed malicious file will no longer be active and it can be easily deleted manually.
Malware Disinfection Tools
F-Secure provides disinfection tools for certain malware. These tools can be downloaded from this webpage:
http://www.f-secure.com/download-purchase/tools.shtml
ftp://ftp.f-secure.com/anti-virus/tools/
Windows System Restore Issues
If Windows ME or XP is used, it is recommended to disable System Restore feature of these operating systems to prevent a computer from re-infection by an already removed malware. The fact is that System Restore feature of these operating systems might save an infected file into the special folder and copy it back to a hard drive it every time it's been renamed or deleted by F-Secure Anti-Virus or by a user. Instructions on how to disable System Restore feature are here:
Windows ME:
http://www.f-secure.com/v-descs/sfc_dis.shtml
Windows XP:
http://www.f-secure.com/v-descs/sfc_dis1.shtml
It is recommended to re-enable System Restore after disinfection in order to restore stable system configuration in the future, if any crash or incompatibility issue occurs.
Failed Disinfection
In some cases F-Secure Anti-Virus might not disinfect a system automatically. In this case please visit our Support pages:
http://support.f-secure.com/enu/home/virusproblem/howtoclean/
Usually standalone malware (backdoors, worms, trojans, etc.) is automatically removed by F-Secure Anti-Virus (FSAV) starting from version 5.40. Malware files get automatically renamed by FSAV, so they can not be started any more. In some rare cases, when automatic disinfection is not possible, a user can select disinfection action by him/herself to make FSAV rename or delete an infected file. In some special cases it is recommended to use specific disinfection tools provided by F-Secure. They can be downloaded from our ftp site:
ftp://ftp.f-secure.com/anti-virus/tools/
F-Secure Anti-Virus can be purchased from our webshop or from our authorised distributors. A trial version F-Secure Anti-Virus, limited to 30 days, can be downloaded from our website:
http://www.f-secure.com/download-purchase/
All the latest versions of FSAV can download anti-virus database updates automatically. However, these updates can be also downloaded and installed manually from our web or ftp sites:
http://www.f-secure.com/download-purchase/updates.shtml
Manual Disinfection
To manually disinfect standalone malware (backdoors, worms, trojans, etc.) it's usually enough to delete all infected files from a computer and to restart it. Active malware files are usually locked by operating system so different disinfection approaches are required for different operating systems.
Please note that manual disinfection is a risky process, so it is recommended only for advanced users.
If Windows 95, 98 and ME operating system is used, it is recommended to restart a computer from a bootable system diskette and to delete an infected file from command prompt. For example if a malicious file named ABC.EXE is located in Windows folder, it is usually enough to type the following command at command prompt:
DEL C:\WINDOWS\ABC.EXE
and to press Enter. After that an infected file will be gone. If Windows NT, 2000 or XP is used, a malicious file has to be renamed with a different extension (for example .VIR) and then a system has to be restarted. After restart a renamed malicious file will no longer be active and it can be easily deleted manually.
Malware Disinfection Tools
F-Secure provides disinfection tools for certain malware. These tools can be downloaded from this webpage:
http://www.f-secure.com/download-purchase/tools.shtml
ftp://ftp.f-secure.com/anti-virus/tools/
Windows System Restore Issues
If Windows ME or XP is used, it is recommended to disable System Restore feature of these operating systems to prevent a computer from re-infection by an already removed malware. The fact is that System Restore feature of these operating systems might save an infected file into the special folder and copy it back to a hard drive it every time it's been renamed or deleted by F-Secure Anti-Virus or by a user. Instructions on how to disable System Restore feature are here:
Windows ME:
http://www.f-secure.com/v-descs/sfc_dis.shtml
Windows XP:
http://www.f-secure.com/v-descs/sfc_dis1.shtml
It is recommended to re-enable System Restore after disinfection in order to restore stable system configuration in the future, if any crash or incompatibility issue occurs.
Failed Disinfection
In some cases F-Secure Anti-Virus might not disinfect a system automatically. In this case please visit our Support pages:
http://support.f-secure.com/enu/home/virusproblem/howtoclean/
Additional Details
The backdoor's file is a PE executable about 1.3 megabytes long, packed with Themida file compressor.
When the backdoor's file is started, it copies itself as a file named winupdate.exe to the Windows System folder and then creates the following startup key value in the Registry:
When the backdoor is active, it connects to an IRC server, joins a certain channel, and acts as a bot there.
The following IRC server and ports is used by the backdoor:
The backdoor joins the following password-protected IRC channel:
A hacker can send commands to the bots to control infected computers. Several tasks can be performed, including the following:
When spreading, the bot can exploit the following vulnerabilities:
When the backdoor's file is started, it copies itself as a file named winupdate.exe to the Windows System folder and then creates the following startup key value in the Registry:
• [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
"winupdate" = "winupdate.exe"
"winupdate" = "winupdate.exe"
When the backdoor is active, it connects to an IRC server, joins a certain channel, and acts as a bot there.
The following IRC server and ports is used by the backdoor:
• 72.20.15.41:6667
The backdoor joins the following password-protected IRC channel:
• #~>|EBoT|<~
A hacker can send commands to the bots to control infected computers. Several tasks can be performed, including the following:
• Start FTP server
• Perform ping, SYN, ICMP and UDP flooding
• Get system information including OS, network and drives
• Update the backdoor's software
• Operate the backdoor's bot (nick change, join channels et cetera)
• Redirect traffic (proxy)
• Steal CD keys for popular games
• Download and execute files
• Log keystrokes
• Scan and exploit computers vulnerable to exploits
When spreading, the bot can exploit the following vulnerabilities:
• Weak Windows share passwords
• Weak VNC passwords port 5900
• ASN.1 (MS04-007) ports 80, 139, 445
• WKSSVC (MS03-049) port 135
• Symantec Antivirus and Client Security vulnerability ports 2967, 2968
Detection
F-Secure Anti-Virus detects this malware with the following updates:
[FSAV_Database_Version]
Version = 2007-07-16_06.