SEC Consult’s Recent Extensive Data Networks Security Analysis Highlights Serious Security Vulnerabilities Caused By Routers That Promise Encryption Security!
While manufacturers of network routers promise security by using embedded encryption in their routers, it seems the opposite may be true. For years, experts have warned that routers and other network devices cannot make effective security devices. This is because they fail a number of critical security requirements – best practice encryption and key management among them.
SEC Consult’s recent report highlights a serious encryption weakness in ‘embedded routers’ – the hard-coded SSH host keys. Not only are these routers a weak security option, but the encryption key management weakness has exposed customers to man-in-the-middle attacks.
Network World Article, first published Nov 26th 2015
Millions Of Embedded Devices Use The Same Hard-Coded SSH And TLS Private Keys
Thousands of routers, modems, IP cameras, VoIP phones and other embedded devices share the same hard-coded SSH (Secure Shell) host keys or HTTPS (HTTP Secure) server certificates, a study found.
By extracting those keys, hackers can potentially launch man-in-the-middle attacks to intercept and decrypt traffic between users and millions of devices.
Researchers from security firm SEC Consult analyzed firmware images for over 4,000 models of embedded devices from more than 70 manufacturers. In them they found over 580 unique private keys for SSH and HTTPS, many of them shared between multiple devices from the same vendor or even from different ones.
When correlating those 580 keys with data from public Internet scans, they found that at least 230 keys are actively used by over 4 million Internet-connected devices. Around 150 of the HTTPS server certificates they recovered are used by 3.2 million devices and 80 of the SSH host keys are used by 900,000 devices.
The remaining keys might be used by many other devices that cannot be accessed from the Internet, but are still vulnerable to man-in-the-middle attacks inside their respective local area networks.
SSH host keys are used to verify the identity of a device that runs an SSH server. When users connect to such a device for the first time over the encrypted SSH protocol, they get prompted to save the device’s public key, which is part of a public-private key pair.
On subsequent connections, the server’s identity will be verified automatically based on the public key stored on the user’s SSH client and the private key stored on the device.
If an attacker steals the device’s SSH host private key and is in a position to intercept the user’s connection attempts, he can impersonate the device and trick the user’s computer to talk to his machine instead.
Senetas high-assurance security comments
The security vulnerabilities found in routers featuring embedded encryption, and the fact that they provide added exposure to man-in-the-middle attacks, add weight to the general ‘best practice’ view of network encryption security.
Robust, standards-based encryption remains the most effective long-term security tool. However, when poorly implemented (such as with ‘bad practice’ encryption key management) the encryption may be rendered ineffective.
The most valuable lessons from SEC Consult’s report are simple. To provide a high-assurance security solution, network encryption solutions must be:
- End-to-end – embedded routers do not provide that
- Separated from other network duties – by remaining separate they do not enable any point of entry
- State-of-the-art – featuring best-practice encryption key management, standards-based encryption and optimised random number generation
In the current climate, there is no room for ‘second best’ or ‘sufficient’ security. Organisations need to become more familiar with the different approaches to high-assurance network security. Encryption provides the best, last line of defence. Once your prevention tools (firewall etc) have been overcome and your network has been breached, encryption protects the data itself – rendering it useless to unauthorised users.