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April 11th, 2011

False positive issue with virus defs 110411-1

Virus definition update 110411-1 contained an error that resulted in a good number of innocent sites being flagged as infected. Generally, all sites with a script in a specific format were affected.

Our virus lab staff discovered the problem quickly after releasing the bad update and immediately started working on a fix. The fix was released about 45 minutes after the problematic update and has version number 110411-2. Anyone who still has this problem is kindly asked to manually update the definitions to the latest version, e.g. by right-clicking the avast taskbar icon (the orange (a) ball), and selecting Update -> Engine and Virus Definitions.


We sincerely apologize for the inconvenience. As this typically only affected remote sites (and not local files), simply updating to the latest definitions should completely solve the issue (no local files have been quarantined).

Categories: General, lab, Technology, Virus Lab Tags:
  • Luis

    Tengo una duda:
    Ayer, después de actualizar a la errática versión de base de datos de virus e indicarme casi todas las webs como amenazas, realicé un análisis profundo con Avast detectando 2842 virus en mi equipo; la mayoría de éstos \virus\ fueron enviados al \baul\ pero otros fueron eliminados directamente.

    Una de las cosas que más me extrañó fue que archivos de programas originales con copyright, y firma validada, fueron considerados como amenazas y siguen en el baul. ¿Debo restaurar dichos archivos o tengo que testear cada uno de mis programas para verificar si han sufrido pérdida de integridad y/o funcionalidad?

    Espero que los archivos eliminados por el antivirus Avast no sean críticos para la correcta operatividad de mi sistema y/o programas y, si así fuese, les agradecería que me indicasen la manera de poder recuperar la estabilidad previa que existía en mi equipo. De todas formas, me queda un buen rato de pruebas para valorar todos los daños.

    Gracias de antemano; y seguiré utilizando AVAST.

  • Luis

    I have a question:
    Yesterday, after upgrading to the erratic release of virus database and tell me almost all of the websites as a threat, I conducted a thorough analysis with Avast detecting 2842 viruses on my computer, most of these “viruses” were sent to the “trunk” but others were disposed of directly.

    One of the things that surprised me was that original program files copyright and validated signatures, were seen as threats and are in the trunk. Should I restore these files or do I have each of my test programs to verify if they have suffered loss of integrity and / or functionality?

    I hope that the files deleted by the antivirus Avast are not critical to the proper operation of my system and / or programs and, if so, could you please indicate how to restore stability after which existed on my computer. Anyway, I have a good time to try to assess all the damage.

    Thanks in advance, and continue to use AVAST.

  • Ivan

    Debes restaurarlos. Como no estan realmente infectados, no te va afectar. No te podria decir que hacer por los archivos eliminados.@Luis

  • “How to remove trojans/adware”

    I had a problem with trojans/adware (exx.exe) but now the problem is solved! Today during boot scan Avast found 6 trojans! I have never experienced such a massive virus attack like the day before, but it seems no harm was done, all the infected files were detected and deleted, and no more suspicious processes on my computer. Thank you very much!

  • qsabe

    I’m using version 6.0.1000 with the latest update. Yesterday AVAST fried all of my software files using htm coding for scripts. I have since reinstalled the destroyed software, and now I would like to get the hundreds of reports from each file out of the virus chest, so it can be used for real problems. As I don’t want to spend all day doing the select-delete-OK process hundreds of times, and I can find no simple way to just empty the thing. Am I missing something, or is there a way to remove all the files in the chest? Thanks in advance.

  • Jason Mashak

    Hi, if you were one of the 4% of our users affected by the bad update:

    After updating with a current virus definition file, you should next:
    1. Open the avast! program
    2. Select “Maintenance”
    3. Select “Virus Chest”
    4. Sort by time moved to Chest
    5. Select files you wish to restore
    6. Right-click and select “Restore”

    After the file restoral, copies of the files will remain in the Virus Chest. We hope these steps will alleviate any confusion, but should anyone need further support, please visit