Summary
This type of trojan secretly downloads malicious files from a remote server, then installs and executes the files.
Removal
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
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
Trojan-Downloader:W32/Zlob is a large family of malicious programs that download and install Spyware and Adware applications such as:
- MalwareWipe
- SpyAxe
- SpyFalcon
- SpywareQuake
- SpywareStrike
- WinAntivirusPro
Many of these applications may also be classified as Rogueware.
Some later Zlob variants include a backdoor component which allow the attacker to manipulate the victim's PC.
Installation
Zlob itself is installed on the system by tricking the user into downloading a fake codec or protection system, such as:
- HQCodec
- iCodecPack
- IntCodec
- iVideoCodec
- JpegEncoder
- KeyCodec
- MedCodec
- Media-Codec
- MMCodec
- MMedia Codec
- PlayerCodec
- PornPassManager
- PowerCodec
- SoftCodec
- TrueCodec
- UpToDateProtection
- VCCodec
- VidCodec
- VidCodecs
- VideosCodec
- X Pass Generator
- XXXCodec
- ZipCodec
Note: Most of the names above are also .com domains as well, e.g. VidCodecs.com.
The installation process creates some of these files (depends on the variant).
- %DESTDIR%\hpXXXX.tmp
- %DESTDIR%\iesplugin.dll
- %DESTDIR%\iesuninst.exe
- %DESTDIR%\isaddon.dll
- %DESTDIR%\isamini.exe
- %DESTDIR%\isamonitor.exe
- %DESTDIR%\isauninst.exe
- %DESTDIR%\ishost.exe
- %DESTDIR%\ismon.exe
- %DESTDIR%\isnotify.exe
- %DESTDIR%\issearch.exe
- %DESTDIR%\ldXXXX.tmp
- %DESTDIR%\mscornet.exe
- %DESTDIR%\mssearchnet.exe
- %DESTDIR%\nvctrl.exe
- %DESTDIR%\pmmon.exe
- %DESTDIR%\pmsngr.exe
- %DESTDIR%\pmuninst.exe
Based on the variant of Zlob, %DESTDIR% represents:
- Windows\System32 folder
- Folder located in the Program Files, named the same as the fake codec. For example: C:\Program Files\IntCodec\
During installation, the following registry keys and Class IDs are created:
- HKEY_CLASSES_ROOT\CLSID\
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\SharedTaskScheduler
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\explorer\run
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\ShellServiceObjectDelayLoad
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objecta
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
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