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Backdoor.Juasek

Posted: August 24, 2012

Threat Metric

Threat Level: 6/10
Infected PCs: 80
First Seen: August 24, 2012
OS(es) Affected: Windows

Backdoor.Juasek is a backdoor Trojan that allows criminals to exert control over your PC through a C&C server, with potential attacks including disabling security applications, stealing personal information or installing other malware. SpywareRemove.com malware experts have also taken note of Backdoor.Juasek's default tendency to overwrite normal system files with malicious ones, which allows Backdoor.Juasek to launch automatically and may require a restore or repair of Windows. Most components of a Backdoor.Juasek infection should be removed by anti-malware software immediately, since Backdoor.Juasek, despite being low in distribution, has a payload that's capable of causing not-insignificant harm to your PC.

How Backdoor.Juasek Turns Windows Against Itself

Backdoor.Juasek's main components center around usage of a malicious DLL file that's created with a semi-random name. The name of this DLL file is chosen from a list (including such entries as sparksrv or espdate) and then copied into your Windows system folder. If necessary, Backdoor.Juasek will overwrite any original DLL in that location that shares the same name as the malicious DLL that Backdoor.Juasek creates. Additional Registry-based changes to Windows allow Backdoor.Juasek to tamper with your security settings and initiate its own automatic startup. A second DLL file also is created to serve as a configuration log file. SpywareRemove.com malware researchers note that these system changes happen without your consent or distinct symptoms.

After its installation is finished, Backdoor.Juasek can be used through remote servers for any number of attacks, with noteworthy functions listed below:

  • Backdoor.Juasek may delete files.
  • Backdoor.Juasek may launch Command Prompt commands of its own accord (to enumerate files, delete them, change their names, move them to new locations, etc).
  • Backdoor.Juasek may launch files without your consent; SpywareRemove.com malware experts emphasize that this includes installers for other types of hostile software.
  • Backdoor.Juasek may add data to arbitrary files – such as log files that store stolen passwords and other personal information.
  • Backdoor.Juasek can also be used to retrieve general data about active-in-memory processes or files on your hard drive.
  • Lastly, Backdoor.Juasek may also load and exercise function-specific usage of other malicious DLLs. This allows Backdoor.Juasek to benefit from a semi-modular structure and use related PC threats for other attacks against your computer.

Surveying the Next PC on Backdoor.Juasek's Hit List

Given that Backdoor.Juasek is a very recently-identified PC threat, its full propagation strategies haven't yet been uncovered, and anti-malware programs may require updates to delete Backdoor.Juasek completely. However, SpywareRemove.com malware researchers do note that all versions of Windows are affected by Backdoor.Juasek.

Aliases of Backdoor.Juasek can include Backdoor.Win32.Juasek.A, Trojan.NTROOTKIT.12883, AGENT3.BOQV, W32/DX.BDK4!TR and WIN32/AGENT.GJQRTQC. Because most components of a Backdoor.Juasek infection either portray themselves as Windows components or hide in sensitive locations, manual removal of Backdoor.Juasek is considered inadvisable.

Technical Details

File System Modifications

Tutorials: If you wish to learn how to remove malware components manually, you can read the tutorials on how to find malware, kill unwanted processes, remove malicious DLLs and delete other harmful files. Always be sure to back up your PC before making any changes.

The following files were created in the system:



file.exe File name: file.exe
Size: 114.68 KB (114688 bytes)
MD5: 233947bd9ac50e8c9e7f4d78e8c42fd2
Detection count: 6
File type: Executable File
Mime Type: unknown/exe
Group: Malware file
Last Updated: September 3, 2012
file.exe File name: file.exe
Size: 45.09 KB (45090 bytes)
MD5: a42f4749820747d7b74c5322b1898a62
Detection count: 5
File type: Executable File
Mime Type: unknown/exe
Group: Malware file
Last Updated: September 3, 2012
%System%/svsdll.log File name: %System%/svsdll.log
Mime Type: unknown/log
Group: Malware file
%System%/[RANDOM FILE NAME].dll File name: %System%/[RANDOM FILE NAME].dll
File type: Dynamic link library
Mime Type: unknown/dll
Group: Malware file

Registry Modifications

The following newly produced Registry Values are:

HKEY..\..\{Value}HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WMNet\Security\"Security" = "[HEXADECIMAL CHARACTERS]"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost\"WMNet" = "multi:"WMNet\00""HKEY..\..\..\..{Subkeys}HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WMNetHKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_WMNET
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