"Cannot open the file because the file format or extension is invalid" opening Office files

"Cannot open the file because the file format or extension is invalid" opening Office files

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UPDATE:

Upon further analysis of the files that have been submitted to us for investigation, the analysts

have determined that the files are encrypted with a private and public key.

Unless the private key is available, the files will not be able to be recovered.

The private key is more than likely held by the attacker.The premise of ransom ware such as this is

that if a person pays the ransom, a key is provided to unlock the files.

The best course of action is to clean up the malware and then restore files from a backup.

 

  We have identified the malware as a new family of ransomware

 

 

Definition Information:

    Latest public Endpoint AM defs:  1.157.1542.0   (Expect several hours later for 1.157.1559.0 or higher)
     http://www.microsoft.com/security/portal/definitions/whatsnew.aspx

    Latest Prerelease AM defs: 1.157.1542.0  (Expect several hours later for 1.157.1559.0 or higher)
     http://www.microsoft.com/security/portal/shared/prereleasesignatures.aspx

 

The signatures are now updated. You should be able to use Safety Scanner to detect and clean it. It does NOT clean your documents, so you will want to restore from a backup after cleaning the malware from your system.



 

More Information:

 

We are currently investigating an ongoing situation where users may encounter an error when trying to open Office documents.

The error can happen opening any Office file type, not just Excel files as shown in the image below. The error says:

"Cannot open the file ... because the file format or extension is not valid. Verify, that the file has not been corrupted and that the file extension matches the format of the file."

 

 

  

   

It's recommended you update the definitions in your antivirus software and run a complete scan of the affected machine(s).

 

When opening binary Word (.DOC) files that are attributed with this issue, Word does not know how to open, so you receive a dialog for File conversion as shown below.

 

We've had reports of it affecting Word documents, Excel files, PowerPoint files and Access databases.

 

Other Support Blog links

 

 

_____________________________________________________________________________

Security EssentialsMicrosoft Security Essentials  http://www.microsoft.com/security/pc-security/mse.aspx

 

Comments
  • I got the same problem as everyone. My Pc is clean. But the virus still got time to encrypt a lot of PDF, JPG, DOC, DOCX, XLS, XLSX Files. I tried a lot of tools for trying to repair, decrypt, recover thos files and none of them works. If anyone got a solution please post it ! Thank you

  • Facing same problem on all office files and JEPG...Please let me know if get the solution anyone...

  • I got the same problem as everyone in this forum. Like Sebastian, my pc is clean, but all my files are still encrypted or corrupted. I have tried so many decrypter but nothing is working. PDF, DOC, DOCX, XLS, XLSX are corrupted. Please if someone find a solution, write it down.

  • Same here on a Windows 8.1 Pro w SSD. Started a couple of weeks ago. Some files get corrupted and others don't - completely random. Have no issues on my older HP with Win7 and MS Office 2010. Been investigating this for 3 days with fingers pointing everywhere; Cryptolocker virus, Skydrive, new WIN8.1, etc. Have 3 anti-virus and none detected a virus. Ran and re-ran sfc /scannow countless times and nothing comes up. Tried one forum where they suggested to reboot with Memcheck - after hours of testing, no errors found. Extremely frustrated. Everything backed up on Egnyte is of no use since files uploaded are also corrupted or gets corrupted as soon as old version gets downloaded. Running out of options and sources to find solutions.

  • should we stop using Microsoft windows .more than 6 months with no solution only Microsoft can sale us bad product when it reach supports we will see them totally silent we will change our file server to linux

  • Please let us know if you found any solution we are affected

    fadishaya@gmail.com

  • Please let us know if you found any solution we are affected

    fadishaya@gmail.com

  • Try changing the file extension to older version eg. .pptx to .ppt .docx to .doc

  • i have the same solution..when i recover my office file i cant open my file.... any solution please inform rahulacharya@gmail.com please! whatsaap number +97339517629

  • If it happens completely randomly, does it happen more often to the same group of people? Perhaps an update malfunctioned?
    Reinstall Office? Try XLSX Open File Tool for recovery your documents (http://www.xlsx.openfiletool.com/)

  • This problem spread world wide and still microsoft has no idea how to fix this?

  • C:/User/Appdata/Roaming/microsoft/Excel/Xlstart
    delete all excel file

  • go to
    c:/user/appdata/roaming/microsoft/excel/xlstart
    delete all excel files

  • still no luck guys?

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