According to Adobe’s advisory:
First off, do not download Flash Player from a site other than adobe.com – you can find the link for downloading Flash Player here. This goes for any piece of software (Reader, Windows Media Player, QuickTime, etc.) – if you get a notice to update, it’s not a bad idea to go directly to the site of the software vendor and download the update directly from the source. If the download is from an unfamiliar URL or an IP address, you should be suspicious.
Second, all Adobe software for Windows is signed with a digital certificate that is validated by Windows when you install our software. The Publisher will always be ‘Adobe Systems, Incorporated’, and you can verify this when you double-click the installer, or by right-clicking on the installer, selecting ‘Properties’, and going to the ‘Digital Signatures’ tab.