F-Secure Trojan Information Pages: Agent.AUM
[Summary]
| [Disinfection]
| [Detailed Description]
| [Detection]
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| Name: | Agent.AUM |
| Alias: | Trojan-Dropper.Win32.Agent.aum |
| Size: | 1,695,744 bytes |
| Type: | Trojan |
| Category: | Trojan |
| Platform: | Win32 |
| Date of Discovery: | August 15, 2006 |
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Summary |
Agent.AUM is a trojan that drops and executes several other malware files onto the computer system.
In general, trojan droppers are usually standalone programs that drop different types of standalone malware (trojans, worms, backdoors) to a system. A typical trojan dropper is a file that contains a few other files compressed inside its body. When a trojan dropper is run, it extracts all files it contains to a folder (usually temporary folder) and runs all of them simultaneously.
Aside from being a dropper, this trojan also has the ability to steal usernames, passwords, and other system information from the victim's computer. |
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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/ |
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Detailed Description |
Agent.AUM is a Themida packed trojan that arrives on the system with the filename of Windows Genuine Advantage Patch.exe.
Upon execution, it drops the following files in the Windows System directory:
- ldapi32.exe (17 KB) - Detected as Backdoor.Win32.Cakl.a
- ntcvx32.dll (22 KB) - Detected as Trojan-Spy.Win32.Delf.qb
- ntswrl32.dll (9 KB) - Detected as Backdoor.Win32.Cakl.a
- vssms32.exe (1,696 KB) - A copy of itself
It checks the existence of the following mutex to ensure that there's only one instance of itself running in memory:
In creates the following autostart registry entry:
- [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
vssms32 = "{systemdir}\vssms32.exe"
It also creates the following registry entry to allow itself to bypass the Windows Firewall:
- [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters
\FirewallPolicy\StandardProfile\AuthorizedApplications\List]
{systemdir}\vssms32.exe = "{systemdir}\vssms32.exe:*:Enabled:Dnode"
It modifies the following registry keys:
- [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal]
- [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Network]
- and changes them it to:
- [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\minimal.xxx]
- [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\network.xxx]
This is done in order to prevent the user from successfully booting into Safe Mode.
This trojan tries to steal user account names and passwords of the following known applications:
- Firefox
- ICQ
- Internet Explorer
- MSN Messenger
- Outlook
- RAS
It also tries to get system information such as:
- CapsLock State
- Computer Name
- CPU Name
- CPU Speed
- Free Disk Space
- Local Host Name
- NumLock State
- Operating System
- Resolution
- Screen Captures of the System
- ScrollLock State
- Temporary and System Folders Location
- User Name
- Windows Language
Agent.AUM also attempts to log keystroke events and saves them to the following file located at the Windows folder:
Below is an example of the HKR32.ASM file. It shows the user's logged keystrokes:
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Detection |
F-Secure Anti-Virus detects this malware with the following updates: [FSAV_Database_Version] Version = 2006-08-15_07.
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F-Secure Corporation |
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