Meta’s Muse assistant is exposing user conversations through share links that can be found by anyone, according to researchers at the security firm Claroc. The team enumerated 6,800 links that Muse users had created to share chats and found sensitive material in the few hundred it opened, including information that was clearly meant to stay private. Muse, which Mark Zuckerberg described last month as built from the ground up for privacy and security, requires access to most of a user’s accounts so it can fill out forms, book appointments, make purchases and create documents.
Muse’s sharing works much like other online services: a user chooses an option that generates a unique URL, and anyone with that link can load the page hosting the content. Such links normally carry a long, unguessable string of text to keep sensitive material away from unintended viewers. Claroc found that every Muse share link uses the domain cf.metaaiusercontent.com, and that each one also contains the conversation’s name alongside the long string. Simplified examples the researchers gave include home-sale-budget-9f21c8a3.cf.metaaiusercontent.com and q3-revenue-review-7b1e42f0.cf.metaaiusercontent.com.
Because those titles appear in the web address, they are recorded in public DNS records that anyone can search, the researchers said. Claroc found the links through a passive DNS search, which stores the historical resolution of domain names to IP addresses along with nameserver and mail-server records over time. Such a record is generally created when a monitoring system observes a DNS response, so once the intended recipient clicks a share link, the DNS information lands in a searchable database. Claroc said gathering the links took one query rather than real effort, and called the pages GhostShares, meaning they open for people who were never handed the link and can find it on their own.
Claroc co-founder and CTO Asaf Aprozper said in an email that his company contacted Meta and never received a reply. After checking similar platforms, consulting industry colleagues and re-reading Muse documentation, he wrote, the researchers concluded the behavior is by design. He said users should know that asking Muse to share a chat with someone creates a public link discoverable through the passive-DNS techniques Claroc described. A Meta representative did not immediately have answers to questions sent by email.
Muse quickly rose to one of the top spots in Apple’s App Store, and Meta has marketed the assistant as a platform deserving of the extraordinary trust it needs to operate. Three weeks after launch, macOS security expert Patrick Wardle found a zero-day vulnerability that let any other app on the same device take complete control of a user’s Muse account. Meta downplayed the severity, saying exploitation was not possible unless a device was already compromised, and did not acknowledge Wardle’s finding that a simple ClickFix attack was enough to hijack an account.
The ease of finding share links adds to questions about whether Muse merits the access it requires. Claroc’s findings suggest users should limit the personal information they discuss in conversations and delete share links as soon as possible.
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