I have discovered another security flaw in Samsung Android phones. It is possible to completely disable the lock screen and get access to any app - even when the phone is "securely" locked with a pattern, PIN, password, or face detection. Unlike another recently released flaw, this doesn't rely quite so heavily on ultra-precise timing.
This does not occur on stock Android from Google. This flaw only seems to be present on Samsung's version of Android. I have only tested it on a Galaxy Note II running 4.1.2 - I believe it should work on Samsung Galaxy SIII. It may work on other devices from Samsung.
My test phone was running 4.1.2 with the Touchwiz launcher from Samsung.
Defending Against This Attack
Until Samsung release a patch, the only way this can be defended against is by completely removing the Samsung firmware and replacing it with a 3rd party ROM. This ROM for the Galaxy S III claims to have fixed the problem. I'm sure there will be ROMs for other Galaxy devices in due course.
I reported this flaw to Samsung in late February. They are working on a patch which they assure me will be released shortly. I have delayed public disclosure of this vulnerability. I also asked if they wanted me to delay publication until a patch was ready - however they declined this offer.
If you discover a security issue with Samsung's mobile products, I strongly encourage you to email m.security AT samsung.com
They will provide their PGP public key if you wish to ensure your communications with them are secure.