Trojan-Downloader:W32/Exchanger

Classification

Category:Malware

Type:Trojan-Downloader

Platform:W32

Aliases:

Trojan-Downloader:W32/Exchanger, Trojan-Downloader.Win32.Exchanger

Summary

Trojan-Downloader:W32/Exchanger variants download additional malicious software onto the infected system.

Removal

Manual action

To manually remove a Trojan-Downloader:W32/Exchanger infection, perform the following steps:

Open the Windows Task Manager by pressing the Ctrl + Alt + Delete keys and click the Task Manager button.
From the list of running processes, find CbEvtSvc.exe and then click the End Process button.
You may close the Task Manager once the malicious process is terminated.
From the Windows Start Menu, select Run, type regedit into the "Open:" field and then click OK.
From the Registry Editor, locate and delete the following keys if present:
Note: HKLM equals HKEY_LOCAL_MACHINE
Delete the file called CbEvtSvc.exe located in the C:\WINDOWS\system32\ folder.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

Check for the latest database updates
First check if your F-Secure security program is using the latest updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note: You need administrative rights to change the settings.

Technical Details

Once the trojan is executed it copies itself into the "system32" folder and starts itself from there as a service.The trojan also creates Windows registry entries to ensure that it is started every time the computer is started.Once running, Exchanger variants will attempt to contact a remote server in order to relay information about the infected machine. The server will reply with a list of URLs that point to malicious files to be downloaded.

File System Changes

Creates these files:

%windir%\system32\CbEvtSvc.exe

Process Changes

Creates these processes:

%windir%\system32\CbEvtSvc.exe

Registry Modifications

Sets these values:

HKLM\System\CurrentControlSet\Services\CbEvtSvc Type = 00000010 Start = 00000002 ErrorControl = 00000001 ImagePath = %SystemRoot%\System32\CbEvtSvc.exe -k netsvcs DisplayName = CbEvtSvc ObjectName = LocalSystem Opt =
HKLM\System\CurrentControlSet\Services\CbEvtSvc\Security Security = \x01\x00\x14\x80\x90\[...]

Creates these keys: