Akamai identifies new abuses of OpenSSH vulnerability

Akamai Technologies, Inc., the content delivery network (CDN) services provider, has published new research from the company's Threat Research team.

Akamai researchers Ory Segal and Ezra Caltum have identified a recent spate of attacks whereby attackers are using Internet of Things (IoT) devices to remotely generate attack traffic by using a 12-year old vulnerability in OpenSSH, which we are calling SSHowDowN Proxy.

Overview

It is important to note that the research and subsequent advisory do not introduce a new type of vulnerability or attack technique, but rather a continued weakness in many default configurations of Internet-connected devices. These devices are now actively being exploited in mass-scale attack campaigns against Akamai customers.

The Threat Research Team has observed SSHowDowN Proxy attacks originating from the following types of devices:

• CCTV, NVR, DVR devices (video surveillance)
• Satellite antenna equipment
• Networking devices (e.g. Routers, Hotspots, WiMax, Cable and ADSL modems, etc.)
• Internet connected NAS devices (Network Attached Storage)
• Other devices could be susceptible as well

Compromised devices are being used for:

• Mounting attacks against a multitude of Internet targets and Internet-facing services, such as HTTP, SMTP and Network Scanning
• Mounting attacks against internal networks that host these connected devices

Once malicious users access the web administration console, they have been able to compromise the device's data and, in some cases, fully take over the machine.

"We're entering a very interesting time when it comes to DDoS and other web attacks; 'The Internet of Unpatchable Things' so to speak," explained Ory Segal, senior director, Threat Research, Akamai. "New devices are being shipped from the factory not only with this vulnerability exposed, but also without any effective way to fix it. We've been hearing for years that it was theoretically possible for IoT devices to attack. That, unfortunately, has now become the reality."

Mitigation

Some recommended approaches to mitigation include:

• If the device offers access to alter the SSH passwords or keys, change those from the vendor defaults.
• If the device offers direct file system access:
• Add "AllowTcpForwarding No" into the global sshd_config file.
• Add "no-port-forwarding" and "no-X11-forwarding" to the ~/ssh/authorized_ keys file for all users.
• If neither option above is available, or if SSH access is not required for normal operation, disable SSH entirely via the device's administration console.

If the device is behind a firewall, consider doing one or more of the following:

• Disable inbound connections from outside the network to port 22 of any deployed IoT devices
• Disable outbound connections from IoT devices except to the minimal set of ports and IP addresses required for their operation.