U.S. Government Issues Warning on iOS ‘Masque Attack’

The United States Computer Emergency Readiness Team, part of the U.S. Department of Homeland Security, has issued a formal alert on the Apple iOS ‘Masque Attack’.

 

A few days ago FireEye mobile security researchers discovered an iOS security flaw that lets attackers replace your real apps with malware. FireEye found that when installing an app using enterprise/ad-hock provisioning, it could replace a genuine app if it had the same bundle identifier.

Here’s the official alert number TA13-317A:

Systems Affected
iOS devices running iOS 7.1.1, 7.1.2, 8.0, 8.1, and 8.1.1 beta.

Overview
A technique labeled “Masque Attack” allows an attacker to substitute malware for a legitimate iOS app under a limited set of circumstances.

Description
Masque Attack was discovered and described by FireEye mobile security researchers.[1] (link is external) This attack works by luring users to install an app from a source other than the iOS App Store or their organizations’ provisioning system. In order for the attack to succeed, a user must install an untrusted app, such as one delivered through a phishing link.

This technique takes advantage of a security weakness that allows an untrusted app—with the same “bundle identifier” as that of a legitimate app—to replace the legitimate app on an affected device, while keeping all of the user’s data. This vulnerability exists because iOS does not enforce matching certificates for apps with the same bundle identifier. Apple’s own iOS platform apps, such as Mobile Safari, are not vulnerable.

Impact
An app installed on an iOS device using this technique may:
● Mimic the original app’s login interface to steal the victim’s login credentials.
● Access sensitive data from local data caches.
● Perform background monitoring of the user’s device.
● Gain root privileges to the iOS device.
● Be indistinguishable from a genuine app.

Solution
iOS users can protect themselves from Masque Attacks by following three steps:
● Don’t install apps from sources other than Apple’s official App Store or your own organization.
● Don’t click “Install” from a third-party pop-up when viewing a web page.
● When opening an app, if iOS shows an “Untrusted App Developer” alert, click on “Don’t Trust” and uninstall the app immediately.

Further details on Masque Attack and mitigation guidance can be found on FireEye’s blog [1] (link is external). US-CERT does not endorse or support any particular product or vendor.

Check out more details on Masque Attack.