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Poor SSL Implementations Leave Many Android Apps Vulnerable
Trailrunner7 writes "There are thousands of apps in the Google Play mobile market that contain serious mistakes in the way that SSL/TLS is implemented, leaving them vulnerable to man-in-the-middle attacks that could compromise sensitive user data such as banking credentials, credit card numbers and other information. Researchers from a pair of German universities conducted a detailed analysis of thousands of Android apps and found that better than 15 percent of those apps had weak or bad SSL implementations. The researchers conducted a detailed study of 13,500 of the more popular free apps on Google Play, the official Android app store, looking at the SSL/TLS implementations in them and trying to determine how complete and effective those implementations are. What they found is that more than 1,000 of the apps have serious problems with their SSL implementations that make them vulnerable to MITM attacks, a common technique used by attackers to intercept wireless data traffic. In its research, the team was able to intercept sensitive user data from these apps, including credit card numbers, bank account information, PayPal credentials and social network credentials."
I have now read the article and it is apps misuse the APIS. They search for apps that either don't use the TLS APIs but have ssl addresses encoded, or which use a non-default trust manager. When you establish an SSL connection via the normal Java APIs the default trust manager does check the validity of the certificates (i.e. that tey are signed by a trusted CA) and that the URL requested matches the hostname in the certificate's subject DN. There can be valid reasons for overriding this, including using your own specific certificate rather than any signed by a CA, or for development to allow self-signed certificates - though this should be put in production.
They found that a lot of apps had overridden the rust manager in a dangerous way, allowing self-signed certificates in production or allowing any certificate even if id didn't match the host.
Though this is a problem it is not an "android issue". You can write apps that use self-signed certificates, bypass host checking etc. on Windows and any platform that allows you to customise certificate trust checking.
The problem does not always lie in the certificate. It also lies in the fact that the SSL clients built into Windows NT 5.1 (XP) Android 2.3 (Gingerbread) does not support Server Name Indication (SNI), which allows multiple certificates on one IP address. This lack of support for SNI was not corrected until Windows NT 6 (Vista) on PCs, Android 3.0 (Honeycomb) on tablets, or Android 4.0 (ICS) on phones and pocket tablets. Without SNI and without DNSSEC, each site using SSL needs its own IP address.