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copz

Is there any way to check if a program has been tampered with before you download it.

Cork Skate

copz wrote: »

Is there any way to check if a program has been tampered with before you download it.

Are you downloading it from a dodgy website? Why bother, save yourself the hassle and look for it elsewhere.

copz

Thats not what I mean, is it possible in some to verify the download.
like inserting sypware in the code.

Snowbat

Most large download sites (like CNET) screen for malware and spyware and ensure that the software they distribute complies with their policies but there isn't any way¹ for *you* to check files before you download them.

After download, there are possibilities. You could scan the file at http://www.virustotal.com/ (42 AV products) before running it. You could upload it to the Norman Sandbox and get a report about what the program does when it runs (such as trying to connect to external websites).

You could md5sum the file and compare the checksum to one supplied by the publisher (and/or the checksum of a known-good copy). Many Linux distributions use GPG-signed packages and Package Managers that automatically check file integrity (md5sum) and authenticity (GPG signature) of downloaded packages before installation. In Windows, installers such as InstallShield and Windows Installer have an option for the publisher to digitally sign files with similar integrity and authenticity checks. However, these methods only protect distribution - if the publisher decides to do something nasty or loses control of their signing key, you're back to square one.



¹ If you had a shell on the server, you could ssh in and run md5sum or sha1sum on the file before you download it, but that kind of access is normally only available to the server owners.

copz

Thanks snowbat:)