The first line of defense against smartphone snoops is a handset's lock screen, but the two largest smartphone makers are having trouble keeping them secure.

Bugs were discovered Wednesday in both Android and Apple smartphones, just a day after Apple released iOS 6.1.3 to fix a previous passcode bug.

The new lock screen bug was discovered in Apple's iPhone by a reader of the Cult of Mac website. It uses an iPhone's control feature to bypass the lock screen. However, the exploit appears to only work on the iPhone 4.

When a call is voice dialed, the publication explained, if the phone's SIM card is ejected during the dial-up, the phone will display its recent call log. From that screen, a peeper can browse and edit contacts and add pictures to the phone.

Meanwhile, a bug discovered by Android researcher Terence Eden allows anyone to bypass the security measures in place at a phone's lock screen and gain total access to the contents of a handset.

Eden outlined the method for bypassing the lock screen in his personal blog. The technique exploits the 911 feature of a phone, which allows emergency calls to be made whether a phone is locked or not.

The researcher noted that he found his attack to work only on a Samsung version of Android. It does not work on phones running a stock version of Android from Google.

He tested the attack on a Galaxy Note II from Samsung, but he predicted it would also work on a Samsung Galaxy III, as well as other Samsung devices, too.

Samsung did not respond to a request for comment for this story.

Eden explained that he reported the bug to the company in February, and that he expected a bug fix to be issued shortly.

[Slide show: 10 tips for Android security]

Both the Android and Apple bugs are similar, according to Diogo Monica, a security engineer with Square, a mobile payments company in San Francisco.

"They both exploit the emergency call system," he said in an interview. "When an emergency call is made, it allows a logic bug to be exploited and let you access the screen without authentication."

Once the lock screen is bypassed, not only can the information in it be eyeballed, but it can be copied, too. If your phone is unlocked, it can be connected to a computer and its contents dumped to the device, Monica explained.

He estimated that all the important data in a phone can be siphoned into a computer in a couple of minutes. A complete data dump of everything in a phone would take a maximum of 15 minutes.

Faulty lock screens would create serious concerns for corporations, maintained Glenn Chisholm, CSO and vice president of Cylance, a cyber security firm in Reston, Va.

"When you try to access your corporate mail, it usually forces you to enable your lock screen," he explained in an interview. "If the corporation can't trust a lock screen to protect their corporate information ... that's a big problem."

Another big problem for corporations is lost or stolen smartphones, added Giri Sreenivas, vice president and general manager of mobile for Rapid7.

To mitigate those risks, companies require their employees to secure their phones with a PIN. "These vulnerabilities allow those controls to be bypassed," he said in an interview.

Read more about wireless/mobile security in CSOonline's Wireless/Mobile Security section.

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