Don’t let mobile malware steal your company data

It’s closer than you think

The mobile malware landscape is changing. Standardisation might be a good thing for building ecosystems and making phones more useful, but the emergence of Android and iOS as leaders in the operating-system wars makes life easier for those who would target the data on your corporate devices.

It also means there is more to steal, with the ability to generate revenue through reversed billed text, calls to premium-rate numbers and banking on mobile devices.

It is common practice to prohibit user-bought laptops from the corporate network and most employees accept this, yet the rules are different for phones.

Secret agents

According to security researchers, back-door Trojans, which steal data without the victim’s knowledge, and malware that goes after banking login information made up the largest portion of all new mobile malware families in Q2 2013, adding 17,000 strains to their database.

We have recently seen a number of spy-phone Trojans. They include Android Backflash, which installs an icon that looks like Adobe flash and opens a back door, and the BadNews bug, which was found in 32 different apps on Google Play.

This installed a downloader, which in turn called in a premium SMS dialler. Estimates range between two and nine million infections.

Mobile malware is no longer a threat that is still over the horizon. And it is not just spammers and crooks who are out to get you.

Knowing what you are fighting is an important part of protection, says Charles Brookson of mobile consultancy Azenby.

Brookson designed the A5/1 and subsequent encryption standards for GSM. He heads the security group of the European Telecommunications Standards Institute and the GSM Association security group, so he is not just a person who knows about mobile security but one who draws up the rules.

Hell hath no fury

Brookson points out that falling foul of general malware is very different to being targeted by a rival, jealous spouses or governments.

The three ‘E’s of mobile data security are engineering, enforcement and education. Perhaps the most common type of engineering solution is the secure container. This takes the form of a sand-boxed run-time environment, often based on the NSA-derived Security-Enhanced Linux.

Daniel Brodie of Lacoon Mobile Security explains: “This is done by encrypting the data on the phone and providing additional data security features, such as copy-paste data loss prevention.

“A common scenario is for secure containers to enable companies to perform a remote-wipe only on an ex-employee’s business data, rather than removing all mobile data, thus relieving the anguish (and possibly also the legal ramifications) of deleting the employee’s personal photographs as well.“

The secure container can be on a standard phone. The US security firm General Dynamics bought the company OK Labs for its security container, which it runs on LG phones sold to the US marines.

The recent vulnerability in the Exynos5 chipset in the drivers used by the camera and multimedia devices creates a hidden Suid (set owner user ID) binary and uses it for privileged operations, such as reading the mobile logs. The file is placed in an execute-only directory, which allows it to remain hidden from most root detectors.

The spy-phone listens to events in the Android debug bridge logs. These logs, and their corresponding access permissions, differ between Android versions. For versions 2.3 or less, it is possible to simply use the logging permissions.

For Android version 4.0 and higher, root permissions are required to view the logs. The spy-phone waits for a log event that signifies that the user is reading an email; by dumping the heap it can work out the email structure and send the mail on to whoever is doing the spying.

This of course needs both a very determined attack and a set of circumstances, but the engineering lesson here is to keep operating systems up to date.

Down to earth

The main reason most security professionals praise BlackBerry's security is its end-to-end service. Keeping control of the servers is as important as keeping control of the device.

It is not just the data on the device that companies need to worry about. According to Brookson, mail should be hosted on a server at the company premises.

This might be hugely unfashionable in the era of the cloud. But really, if your users are backing up their most sensitive data over the air, you should know where they are backing it up to.

And don’t forget voice. Many companies have to record calls for regulatory reasons. In the UK this is mandated by the Financial Conduct Authority, which was set up in the fallout of the bank mis-selling scandal.