Google in February implemented in its Google Play (formerly Android Market) a technology called Bouncer to check apps submitted by Android developers for any traces of malicious code. This week at the Black Hat Conference in Las Vegas, security firm Trustwave will demonstrate and discuss how it's possible to circumvent the Google Bouncer security check.
Trustwave proved to itself that its masking technique could get past Bouncer's detection by getting a malicious app it created into Google Play earlier this year, says Nicholas Percoco (shown here), senior vice president and head of Trustwave's SpiderLabs advanced security team. "We wanted to test the bounds of what it's capable of," he says, describing how Trustwave as a registered Android developer created an app called "SMS Blocker." When downloaded to a smartphone, the app would be able to steal contacts, SMS messages and photos, and basically know anything about the device. The app could also make the phone go to arbitrary Web pages or launch a denial-of-service attack. He says: "Google never flagged it."
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Percoco notes that Trustwave deliberately chose an SMS blocker to be its test project against Google Bouncer because there are so many of them already on Google Play, and by pricing its SMS Blocker app high, there was little likelihood anyone would actually buy and download it (no one did). But by getting the malicious app past Bouncer for more than two weeks -- Bouncer, which does repeat checks, never spotted it -- Trustwave says it's making the point that sophisticated attacks are likely to evade such malware detection tools.
"As an attack, all a malware attacker has to do to get into Google Play is to bypass Bouncer," Percoco points out. Bouncer's automated detection method isn't yet sufficient to spot the kind of sophisticated masking techniques that Trustwave will demonstrate at the presentation on Wednesday at Black Hat, he says.
Percoco adds that Trustwave reached out to share its findings with Google, which he says is "a great organization to work with," especially Adrian Ludwig in the Google Android Security division. But Percoco says a more manual approach to testing apps on Android devices for malicious code may be needed to even start to detect what Trustwave came up with as a malware-masking technique.
Stonesoft shows off
Also focusing on evasive attacks at Black Hat this week will be Stonesoft, which is announcing a product called Evasion Prevention System. This appliance is designed to detect and block attacks that rely on what the company calls "advanced evasion techniques."