Baidu Apps Leaked Location Data, Machine Learning Reveals

Two popular apps from Baidu collected data on Android phones and uploaded it to the Internet, potentially allowing the apps to track the user, network security firm Palo Alto Networks stated in an analysis of the apps published on Nov. 24.

The Baidu Search Box and Baidu Maps applications, which have more than 6 million downloads from the US Google Play Store, both collected a variety of device identifiers from the phone on which the applications were installed. A third application, Homestyler - Interior Design & Decorating Ideas, also used a software development kit (SDK) that collects information on the user's device, according to the security firm's researchers.

The data collection did not appear to be malicious, just bad practice, says Jen Miller-Osborn, deputy director of threat intelligence for the Unit 42 research group at Palo Alto Networks.

"That kind of data can be used to track a person [and] establish location data points," she says. "It is not the data that people want to have collected on them without their knowledge."

Mobile apps leaking sensitive data has become a common problem. In one study published in May, researchers from Comparitech found 0.83% of the more than half million Android apps analyzed had errors in their database configurations, exposing sensitive user data. Extrapolating the findings across the Google Play Store suggests that some 24,000 applications leaked information. 

In March, security firm Check Point Software Technologies found 56 applications downloaded more than a million times from the Google Play Store contained malware, dubbed Tekya, that mimicked the user and clicked on ads and banners to generate revenue for the adware operators. 

"Although Google has taken steps to secure its Play store and stop malicious activity, hackers are still finding ways to infiltrate the app store and access users' devices," the researchers stated in a blog post. "Millions of mobile phone users have unintentionally downloaded malicious apps that have the ability to compromise their data, credentials, emails, text messages, and geographical location."

In the latest privacy incident, Palo Alto Networks' Unit 42 researchers found that Baidu's Android Push SDK was collecting and communicating unique identifiers from the mobile devices on which applications ran. While some information — such as the device model, carrier, screen resolution, and network — may not give away too much information, the SDK also collected the MAC address and the International Mobile Subscriber Identity (IMSI) number, which is unique for each person.

The IMSI and the International Mobile Equipment Identity (IMEI) numbers are both sensitive identifiers that can be used by cybercriminals to pose as the subscriber or the device, the researchers stated. 

"Once this data is acquired, cybercriminals can profile users and further extract sensitive information about them," they said in the blog post. "For example, if a cybercriminal gets hold of a phone's IMEI number, they could use it to report the phone as stolen and trigger the provider to disable the device and block its access to the network."

Palo Alto Networks researchers detected the surreptitious data collection using a machine learning component of a spyware detection tool, the company said.

The Google Play Store represents a lucrative target for any malware or spyware author. A malicious app that successfully escapes detection can garner millions of downloads in short order. 

Overall, two-thirds of malicious apps come from the Google Play Store, while 10% come from alternative third-party markets, according to researchers from NortonLifelock. Far from indicating the level of malicious apps in the Google Play Store, the data just underscores the dominance of Google's first-party position in the mobile ecosystem. The researchers found that the ratio of bad applications to legitimate ones was much better on the Google Play Store, 0.6%, compared with other sources, such as alternative third-party markets, which have a 3.2% chance of sourcing unwanted software.

"[U]nwanted app developers have a large incentive to make their apps appear in the Play market since it provides the apps with higher visibility, reputation, and trust," the researchers said. "This leads to a low fraction, but large number overall, of unwanted apps being able to bypass Play's defenses."

Google removed all three apps from the Play Store on Oct. 28, although Baidu fixed the Search Box app and it has since been reposted. Baidu Maps is still not available, according to Palo Alto Networks. Google's Android team acknowledged Palo Alto in a statement on the issue. 

"We appreciate the work of the research community, and companies like Palo Alto Networks, who work to strengthen the security of the Play Store. We look forward to collaborating with them on more research in the future," the team stated in the Palo Alto blog post.