Mobile security research firm Bluebox labs
discovered (and reported to Google) a serious security issue with Android in February that, according to a new announcement, remains unpatched. The discovered flaw allows a miscreant to modify APK code without breaking an app's cryptographic signature. The modification of code can allow a coder to make an app pass through Google's security precautions unnoticed, and elevate permissions allowing malicious code to be executed. The flaw has existed since Android OS v1.6.
Every Android contains a cryptographic signature to ensure to the kernel of the device that an app has not been tampered with. The vulnerability inserts code into an extant app without changing the signature of the app, in essence tricking Android into believing that an app is unchanged from initial installation.
According to Bluebox, the Trojan attack has special significance. The research firm believes that "while the risk to the individual and the enterprise is great (a malicious app can access individual data, or gain entry into an enterprise), this risk is compounded when you consider applications developed by the device manufacturers (e.g. HTC, Samsung, Motorola, LG) or third-parties that work in cooperation with the device manufacturer (e.g. Cisco with AnyConnect VPN) that are granted special elevated privileges within Android -- specifically, System UID access."
Using this elevated access granted by manufacturer-specific apps, a Trojan-attacked app can then read any information on the device, recall all stored passwords, and "essentially take over the normal functioning of the phone and control any function thereof" including, but not limited to, phone calls, SMS messaging, camera use, and call recording.
Bluebox reported the issue to Google earlier this year, but it is believed that no manufacturers have implemented the fix, including Google itself. Full specifics on the assault methodology will be released to the public at the Black Hat 2013 conference.