Justin Case at AndroidPolice.Com says he has discovered a major flaw in some versions Skype for Android which could affect up to 10 million Skype for Android users.
The vulnerability stems from how Skype stores data, such as your contacts, profile, instant message logs, and more. Case says that Skype mistakenly left these files completely unencrypted and with improper permissions, allowing anyone or any application to read them.
Case says it’s possible that a rogue developer could modify an existing application with code to exploit the vulnerability and distribute the application via the Android Market. From there, Case says, “just watch as all that private user information pours in.”
This is an example of poor software development practices. Skype is much more sophisticated than most standard mobile apps, and with the software engineering team that's behind it, I would expect Skype to have better practices around security and the storing of sensitive data in an unencrypted state with improper permissions. Google and the Android Operating system aren't to blame for this one.
Skype Mobile for Verzion appears to be safe and not have the vulnerability.
Acknowledging the vulnerability, Skype's Chief Security Officer, Adrian Asher, wrote in a blog post, “It has been brought to our attention that, were you to install a malicious third-party application onto your Android device, then it could access the locally stored Skype for Android files.” Asher also cautioned users to be mindful of what apps they are downloading. “To protect your personal information, we advise users to take care in selecting which applications to download and install onto their device.”
Justin Case put together a good blog post describing the vulnerability in more detail on a technical level.