Backdoor:W32/IRCBot.AAS
| Name : | Backdoor:W32/IRCBot.AAS |
| Category: | Malware |
| Type: | Backdoor |
| Platform: | W32 |
Summary
This IRCBot connects to an IRC server at dark.bestunix.org. After this, the bot waits for commands from a remote user. The bot is controlled via messages sent to it.
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 themselves 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 web shop or from our authorized distributors. A trial version of 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 is 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 the command prompt. For example, if a malicious file named ABC.EXE is located in the 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 restarting, 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 every time it has 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 if any crash or incompatibility issue occurs in the future.
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 themselves 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 web shop or from our authorized distributors. A trial version of 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 is 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 the command prompt. For example, if a malicious file named ABC.EXE is located in the 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 restarting, 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 every time it has 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 if any crash or incompatibility issue occurs in the future.
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
Upon execution, Backdoor.Win32.IRCBot.AAS drops a copy of itself in the Windows System directory as algose32.exe (e.g. C:\Windows\system32\algose32.exe). This malware connects to an IRC server and joins the channel #!e! with a channel password, using a random nickname. It waits for commands from a remote user. To be able to gain access with the BOT, the remote user should login and type the password of the BOT.
When successfully logged in to the BOT, the remote user can do the following IRC commands:
The remote user can also perform the following system commands:
Autostart Mechanism
This IRCBot creates the following registry key as its auto-start technique:
Note: %systemdir% is typically "C:\Windows\system32".
Additional Information
This BOT takes advantage of MS06-040. The specially crafted packet is embedded in the body of this IRCBot and is XOR'ed by 99h. The BOT will then wait for a "Scan" command from a remote user. In this case, the BOT will send this specially crafted packet to all IP addresses that the remote user specified to the BOT.
The payload of the packet is that it downloads a file from a URL and executes it. The URL that this BOT downloads the file from is http://www.emr3.net/p[removed].exe. The file uploaded on the said link is currently detected as Backdoor.Win32.IRCBot.WT.
When successfully logged in to the BOT, the remote user can do the following IRC commands:
• Joins/Part an IRC channel
• Send private/channel messages
• Change the BOT's nick
• Quits the IRC server.
• Checks the BOT's ID and version.
• Check the up-time of the BOT
• Logout from the BOT.
• Update the BOT.
The remote user can also perform the following system commands:
• Opens/Executes/Downloads files.
• Port scanning.
• Access files through a Shell.
• List/Terminate processes.
Autostart Mechanism
This IRCBot creates the following registry key as its auto-start technique:
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
Offices Monitorse = "%systemdir%\algose32.exe"
Offices Monitorse = "%systemdir%\algose32.exe"
• HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
Offices Monitorse = "%systemdir%\algose32.exe"
Offices Monitorse = "%systemdir%\algose32.exe"
Note: %systemdir% is typically "C:\Windows\system32".
Additional Information
This BOT takes advantage of MS06-040. The specially crafted packet is embedded in the body of this IRCBot and is XOR'ed by 99h. The BOT will then wait for a "Scan" command from a remote user. In this case, the BOT will send this specially crafted packet to all IP addresses that the remote user specified to the BOT.
The payload of the packet is that it downloads a file from a URL and executes it. The URL that this BOT downloads the file from is http://www.emr3.net/p[removed].exe. The file uploaded on the said link is currently detected as Backdoor.Win32.IRCBot.WT.