Samsung Responds to KNOX MitM Attack “Vulnerability”
About a month ago, we talked about a recent study (PDF) stating that most security vulnerabilities on Android are ultimately due to OEM customizations. And surprise, surprise—this can even happen on devices with technologies designed to protect users.
Late last month, security researchers at Israel’s Ben-Gurion University of the Negev discovered a security vulnerability that allowed a user-installed application to intercept unencrypted network traffic. Rather than describing this as a flaw or bug, Samsung labels the vulnerability a classic Man in the Middle (MitM) attack, which could be launched at any point on the network.
Samsung was also quick to state that this type of attack can be thwarted using existing KNOX technology (or the device-wide VPN support in stock Android):
Android development practices encourage that this be done by each application using SSL/TLS. Where that’s not possible (for example, to support standards-based unencrypted protocols, such as HTTP), Android provides built-in VPN and support for third-party VPN solutions to protect data. Use of either of those standard security technologies would have prevented an attack based on a user-installed local application.
KNOX offers additional protections against MitM attacks. Below is a more detailed description of the mechanisms that can be configured on Samsung KNOX devices to protect against them:
1. Mobile Device Management — MDM is a feature that ensures that a device containing sensitive information is set up correctly according to an enterprise-specified policy and is available in the standard Android platform. KNOX enhances the platform by adding many additional policy settings, including the ability to lock down security-sensitive device settings. With an MDM configured device, when the attack tries to change these settings, the MDM agent running on the device would have blocked them. In that case, the exploit would not have worked.
2. Per-App VPN — The per-app VPN feature of KNOX allows traffic only from a designated and secured application to be sent through the VPN tunnel. This feature can be selectively applied to applications in containers, allowing fine-grained control over the tradeoff between communication overhead and security.
3. FIPS 140-2 — KNOX implements a FIPS 140-2 Level 1 certified VPN client, a NIST standard for data-in-transit protection along with NSA suite B cryptography. The FIPS 140-2 standard applies to all federal agencies that use cryptographically strong security systems to protect sensitive information in computer and telecommunication systems. Many enterprises today deploy this cryptographically strong VPN support to protect against data-in-transit attacks.
Now before we start bashing Samsung’s KNOX technology more than necessary, let’s remember that these kinds of attacks can affect non-KNOX devices as well. Furthermore, sending personal data in unencrypted form is simply asking for trouble. If anything, this should serve as a reminder to use encrypted transfers and connections whenever possible and to be wary about where we store and input our data.