Uedasan

Classification

Malware

Virus

W32

Uedasan, Uedasun

Summary

XM/Uedasan is a macro virus that infects Microsoft Excel 95 workbooks. It contains a destructive payload.

Removal

Automatic action

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.

Suspect a file is incorrectly detected (a False Positive)?

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 detection database 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.

Find out more

Knowledge Base

Find the latest advice in our Community Knowledge Base.

User Guide

See the user guide for your product on the Help Center.

Contact Support

Chat with or call an expert for help.

Submit a sample

Submit a file or URL for further analysis.

Technical Details


Variant:Uedasan.A

XM/Uedasan.A activates when a sheet is deactivated in an infected document. At this point it creates a new workbook, infects it and saves it to Excel's startup directory with a name "TDK-MAC.XLS". Then it removes the following menu items: "View/Toolbars...", "Tools/Macro...", "Window/Unhide", "Tools/Protection" and "Format/Sheet/Unhide".

When this is done, the virus infects every workbook when a sheet is activated. It adds a hidden sheet to a workbook which will contain the virus code module. This sheet is protected with a password "uedasan". It also removes the title, subject, author, keywords and comments from the summary information of the active workbook.

After the active workbook has been infected, the virus will activate its payload from August to the end of year.

In August, it attempts to delete everything from the root of "C:" directory; and from September to December if the time is less than 6:00am, it attempts to delete everything from the current directory.


Variant:Uedasan.B

This variant works in a similar fashion like the XM/Uedasan.A.

When it infects Excel, the file created to the startup directory is named "#1SLIDER.XLA" and during infection this virus will check for several specially named modules as well. For example, if it founds a sheet named "pldt" it shows a message box with the following text:

WARNING : VIRUS DETECTED! NAME : 'MERALCO' 		

The payload is the same as the XM/Uedasan.A.


Variant:Uedasan.D

XM/Uedasan.D is functionally identical with XM/Uedasan.B.