On occasion, even the most well thought-out systems can break down. In the antivirus business, we try hard to minimize something termed false positive. A false positive is merely a mistake or a false alarm. It happens when your antivirus software erroneously identifies a file or a download as being malicious.

The AVAST Virus Lab receives more than 50,000 samples of new potential viruses every single day. There are so many that we cannot look at each individually, so we use techniques with super-techie names like Malware Similarity Search and Evo-Gen. (These techniques are explained in a previous blog post, New Toy in the Avast Research Lab.) When a file is confirmed as malicious, we add it to our virus database. With this amount of new samples, every now and then a false positive occurs. There is no way to avoid it completely, but we try to limit it and its impact.

Over the weekend, avast! Mobile Security erroneously detected the TextSecure app as a Trojan. TextSecure is an app developed by Open Whisper Systems that protects your privacy by encrypting your text and chat messages, which means that they can only be read by your intended recipients. The AVAST Virus Lab discovered the error, fixed it and sent out an update.

Unfortunately, wires got crossed between our Virus Lab analyst and our social media community manager, and the wrong message was sent to people on Twitter and Facebook who inquired about the detection. You see, at the same time as the TextSecure detection was being reported, another unrelated detection was made, and it was indeed a malicious file. It was a simple case of mistaken identity. Later in the day, we discovered the mistake and followed up by communicating it across AVAST social channels.

AVAST confirms that TextSecure Private Messenger is a genuine and safe application for Android, and contains no malicious scripts. We apologize for the inconvenience caused to TextSecure users and Open Whisper Systems.

Please be assured that AVAST does not intentionally recognize valid software as suspicious. The last thing we want to do is disrupt businesses or our customers. However, to provide maximum protection against genuine virus threats, false positive alerts sometimes arise.

How to report a suspected false positive

If you suspect that AVAST has incorrectly identified a file as suspicious, please submit a report to http://www.avast.com/contact-form.php?subject=VIRUS-FILE. This form will generate an email to our Virus Lab research team, and they will investigate it.

Before you do that, you may want to upload a file or a URL to online virus scanning service VirusTotal. This free online service scans the file against multiple antivirus engines and website scanners at the same time.

TextSecure protects your privacy

The fine developers of the TextSecure app deserve a happy ending, so we want to throw our support behind this innovative app. We developed avast! Mobile Security to protect Android users from malware and theft and have included numerous features to protect the privacy of our users. The TextSecure app takes that further by providing end-to-end encryption when you are communicating with other TextSecure users. It also keeps your messages away from prying eyes if your phone is lost or stolen.

Install TextSecure Private Messenger for free from Google Play. Don't forget to leave a review and a 5-star rating!

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