TikTok skirted a privateness safeguard in Google’s Android working system to gather distinctive identifiers from hundreds of thousands of cellular units, knowledge that enables the app to trace customers on-line with out permitting them to decide out, a Wall Road Journal evaluation has discovered.

The tactic, which specialists in mobile-phone safety mentioned was hid by way of an uncommon added layer of encryption, seems to have violated Google insurance policies limiting how apps monitor folks and wasn’t disclosed to TikTok customers. TikTok ended the observe in November, the Journal’s testing confirmed.

The findings come at a time when TikTok’s Beijing-based mum or dad firm, ByteDance Ltd., is underneath stress from the White Home over issues that knowledge collected by the app could possibly be used to assist the Chinese language authorities monitor U.S. authorities staff or contractors. TikTok has mentioned it doesn’t share knowledge with the Chinese language authorities and wouldn’t accomplish that if requested.

The identifiers collected by TikTok, known as MAC addresses, are mostly used for promoting functions. The White Home has mentioned it’s nervous that customers’ knowledge could possibly be obtained by the Chinese language authorities and used to construct detailed dossiers on people for blackmail or espionage.

Downloading TikTok and WeChat from the Google or Apple app shops within the U.S. could possibly be blocked by President Trump’s government orders to limit the Chinese language-owned apps. WSJ watches the markets’ response to grasp what this implies for world enterprise. Picture composite: Sharon Shi

TikTok, which mentioned earlier this yr that its app collects much less private knowledge than U.S. firms akin to

Fb Inc.


Alphabet Inc.’s

GOOG -5.00%

Google, didn’t reply to detailed questions. In an announcement, a spokesperson mentioned the corporate is “dedicated to defending the privateness and security of the TikTok neighborhood. Like our friends, we always replace our app to maintain up with evolving safety challenges.”

The corporate mentioned “the present model of TikTok doesn’t gather MAC addresses.”

Most main cellular apps gather a spread of information on customers, practices that privateness advocates have lengthy discovered alarming however that tech firms defend as offering extremely personalized experiences and focused promoting. Information assortment varies by firm.

About 1% of Android apps gather MAC addresses, in response to a 2018 examine by AppCensus, a mobile-app evaluation agency that consults with firms on their privateness practices.

A Google spokesperson mentioned the corporate was investigating the Journal’s findings and declined to touch upon the loophole permitting some apps to gather MAC addresses.

The Trump administration’s national-security issues prompted ByteDance to discover a sale of TikTok’s U.S. operations with a number of suitors, together with

Microsoft Corp.

When requested if the corporate was conscious of this data-collection difficulty, a Microsoft spokesman declined to remark.

The problem includes a 12-digit “media entry management,” or MAC, deal with, which is a singular quantity present in all internet-ready electronics, together with cellular units.

The MAC deal with is beneficial to advertising-driven apps as a result of it might’t be reset or altered, permitting app makers and third-party analytics corporations to construct profiles of client conduct that persist by way of any privateness measure in need of the proprietor getting a brand new cellphone. The Federal Commerce Fee has mentioned MAC addresses are thought-about personally identifiable info underneath the Youngsters’s On-line Privateness Safety Act.

“It’s a approach of enabling long-term monitoring of customers with none skill to opt-out,” mentioned Joel Reardon, an assistant professor on the College of Calgary and co-founder of AppCensus, Inc. “I don’t see one more reason to gather it.”

Apple Inc.

locked down iPhone MAC addresses in 2013, stopping third-party apps from studying the identifier. Google did the identical two years later in Android. TikTok bypassed that restriction on Android by utilizing a workaround that enables apps to get MAC addresses by way of a extra circuitous route, the Journal’s testing confirmed.

The safety gap is broadly recognized, if seldom used, Mr. Reardon mentioned. He filed a proper bug report concerning the difficulty with Google final June after discovering the newest model of Android nonetheless didn’t shut the loophole. “I used to be shocked that it was nonetheless exploitable,” he mentioned.

Mr. Reardon’s report was concerning the loophole usually, not particular to TikTok. He mentioned that when he filed his bug report, the corporate informed him it already had an analogous report on file. Google declined to remark.

TikTok collected MAC addresses for not less than 15 months, ending with an replace launched Nov. 18 of final yr, as ByteDance was falling underneath intense scrutiny in Washington, the Journal’s testing confirmed.

TikTok bundled the MAC deal with with different system knowledge and despatched it to ByteDance when the app was first put in and opened on a brand new system. That bundle additionally included the system’s promoting ID, a 32-digit quantity supposed to permit advertisers to trace client conduct whereas giving the person some measure of anonymity and management over their info.

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Privateness-conscious customers can reset the promoting ID from the settings menu of the system, an motion roughly equal to clearing cookies in a browser.

Google’s Play Retailer insurance policies warn builders that the “promoting identifier should not be related to personally-identifiable info or related to any persistent system identifier,” together with the MAC deal with, “with out specific consent of the person.”

Storing the unchangeable MAC deal with would permit ByteDance to attach the previous promoting ID to the brand new one—a tactic generally known as “ID bridging”—that’s prohibited on Google’s Play Retailer. “If you happen to uninstall TikTok, reset the advert ID, reinstall TikTok and create a brand new account, that MAC deal with would be the identical,” mentioned Mr. Reardon. “Your skill to begin with a clear slate is misplaced.”

Regardless of the prohibition, ID bridging is pretty widespread, in response to AppCensus, significantly amongst free gaming apps. But it surely seldom includes the MAC deal with, probably the most persistent identifier accessible within the present model of Android.

In a random examine by AppCensus of 25,152 common internet-enabled Android apps in 2018, solely 347, or 1.4%, have been seen utilizing the Android loophole to ship the MAC deal with. Of these, solely 90 have been additionally transmitting the built-in Android ID, which adjustments if the system is reset.

The Journal’s evaluation confirmed a few of the conduct detailed in a widely-discussed nameless Reddit submit in April charging that TikTok transmitted a spread of private knowledge to ByteDance servers, together with the MAC deal with. Google mentioned it’s investigating the claims in that submit.

The Journal examined 9 variations of TikTok launched on the Play Retailer between April 2018 and January 2020.  The Journal’s evaluation was restricted to inspecting what TikTok collects when freshly put in on a person’s system, earlier than the person creates an account and accepts the app’s phrases of service.


How nervous are you about TikTok accessing your private knowledge? Be part of the dialog under.

Aside from the MAC deal with, the Journal’s testing confirmed that TikTok wasn’t amassing an uncommon quantity of knowledge for a cellular app, and it disclosed that assortment in its privateness coverage and in pop-ups requesting the person’s consent throughout set up.

Much less typical are the measures ByteDance takes to hide the information it captures. TikTok wraps many of the person knowledge it transmits in an additional layer of customized encryption.

As with nearly all fashionable apps, TikTok’s Web visitors is protected by the net’s customary encryption protocols, making it unlikely that an eavesdropper can steal info in transit. That makes the extra, customized encryption code TikTok applies to person knowledge seemingly extraneous—until it was added to stop the system proprietor from seeing what TikTok was as much as, mentioned Nathan Good, a researcher on the Worldwide Digital Accountability Council, a watchdog group that analyzes app conduct.

“TikTok’s obfuscation of this knowledge makes it more durable to find out what it’s doing,” Mr. Good mentioned. That added layer of encryption makes it more durable for researchers to find out whether or not TikTok is honoring its privateness coverage and varied legal guidelines. He mentioned he isn’t conscious of a enterprise objective for the encryption.

“It doesn’t present any further degree of Web safety,” agreed Mr. Reardon. “But it surely does imply that we’ve got no transparency into what’s being despatched out.”

It is not uncommon for cellular apps to cover elements of their software program to stop them from being copied by rivals, however TikTok’s encryption doesn’t look like hiding a proprietary secret, mentioned Marc Rogers, vp of cybersecurity technique at Okta, Inc., which offers companies that assist customers securely log in on-line.

“My guess is that the explanation they do that’s to bypass detection by Apple or Google as a result of if Apple or Google noticed them passing these identifiers again they might nearly actually reject the app,” Mr. Rogers mentioned.

Google ought to take away TikTok from its platform, mentioned Sen. Josh Hawley (R., Mo.), in an announcement to the Journal, when apprised of the findings. Sen. Hawley has been essential of TikTok and a hawk towards China usually.

“Google must thoughts its retailer, and TikTok shouldn’t be on it,” he mentioned. “If Google is telling customers they received’t be tracked with out their consent and knowingly permits apps like TikTok to interrupt its guidelines by amassing persistent identifiers, probably in violation of our kids’s privateness legal guidelines, they’ve received some explaining to do.”

Write to Robert McMillan at Robert.Mcmillan@wsj.com

Corrections & Amplifications
Nathan Good is a researcher on the Worldwide Digital Accountability Council, a watchdog group that analyzes app conduct. An earlier model of this text incorrectly spelled his final identify as Wooden. (Corrected on Aug. 11.)

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