Unpatched flaw 'weaponises' Apple AirTags to turn them into the phisherman's friend

XSS vulnerability allows miscreants to hijack phone number field on website


Apple has been accused of ignoring a vulnerability in the Lost Mode functionality of its AirTags location-tracking accessories which would allow an attacker to seed "weaponised AirTags" for harvesting the iCloud credentials of anyone who find them.

Launched back in April, AirTags are compact battery-powered devices you stick to your belongings in order to locate them when misplaced. Apple chief compliance officer Kyle Andeer was very clear that AirTags are in no way a copy of Tile's popular compact battery-powered devices you stick to your belongings in order to locate them when misplaced.

Should your AirTag-equipped thing not be where you thought it was, you can enable Lost Mode. When in Lost Mode, an AirTag scanned via NFC provides a unique URL which lets the finder get in contact with the loser – and it's this page where security researcher Bobby Rauch discovered a concerning vulnerability.

"An attacker can carry out Stored XSS on this https://found.apple.com page by injecting a malicious payload into the AirTag 'Lost Mode' phone number field," Rauch wrote in an analysis of the issue. "A victim will believe they are being asked to sign into iCloud so they can get in contact with the owner of the AirTag, when in fact, the attacker has redirected them to a credential hijacking page.

"Other XSS exploits can be carried out as well like session token hijacking, clickjacking, and more. An attacker can create weaponised AirTags and leave them around, victimising innocent people who are simply trying to help a person find their lost AirTag."

Apple has not commented publicly on the vulnerability nor does it seem to be taking the issue particularly seriously. Speaking to Brian Krebs, Rauch claimed that Apple sat on the flaw for three months – and that while it confirmed it planned to resolve the vulnerability in a future update, the company has not yet done so. Apple also refused to confirm whether Rauch's discovery would qualify for its bug bounty programme and a potential cash payout – a final insult which led to his public release of the flaw.

It's not the first time Apple has stood accused of failing to respond to security researchers. Earlier this month a pseudonymous researcher known as "IllusionOfChaos" dropped three zero-day vulnerabilities affecting Apple's iOS 15 – six months after originally reporting them to the company. A fourth flaw had been fixed in an earlier iOS release, the researcher noted, "but Apple decided to cover it up and not list it on the security content page."

The company has also been experiencing a few problems with the patches it does release. An update released to fix a vulnerability in the company's Finder file manager, capable of bypassing the Quarantine and Gatekeeper security functions built into macOS, only worked for lowercase URLs – although emergency patches released two weeks ago appear to have had better luck.

The AirTag vulnerability did not appear to have been fixed at the time of writing, and while exploitation is perhaps unlikely – given that each "weaponised AirTag" would cost the attacker $29 each or four for $99, making it rather expensive to be indiscriminately seeding around the place – it could knock users' confidence in scanning lost tags, harming the efficacy of the entire system.

"This highlights the ease at which a malicious actor could simply manipulate a victim into unwittingly divulging details on a phishing link," ESET UK security specialist Jake Moore told The Register. "Threat actors are very good at pouncing on emotions such as fear or worry, so in the case of a lost phone or device many people would be likely to proceed with the link without further due diligence in their good deed.

"If Apple were to have had prior warning of this attack vector they may have believed it to be a weak attack with limited chance to exploit. However, as shown in theory, where there is a vulnerability in the field it will remain exploitable and likely to occur."

Apple, as is usual for the company, did not respond to a request for comment in time for publication, and it is not yet clear when the flaw will be patched. ®

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