Netgear leaves admin interface’s TLS cert and private key router firmware

Netgear left in its router firmware key ingredients needed to intercept and tamper with secure connections to its equipment’s web-based admin interfaces.

Specifically, valid, signed TLS certificates with private keys were embedded in the software, which was available to download for free by anyone, and also shipped with Netgear devices. This data can be used to create HTTPS certs that browsers trust, and can be used in miscreant-in-the-middle attacks to eavesdrop on and alter encrypted connections to the routers’ built-in web-based control panel.

In other words, the data can be used to potentially hijack people’s routers. It’s partly an embarrassing leak, and partly indicative of manufacturers trading off security, user friendliness, cost, and effort.

Security mavens Nick Starke and Tom Pohl found the materials on January 14, and publicly disclosed their findings five days later, over the weekend.

The blunder is a result in Netgear’s approach to security and user convenience. When configuring their kit, owners of Netgear equipment are expected to visit https://routerlogin.net or https://routerlogin.com. The network’s router tries to ensure those domain names resolve to the device’s IP address on the local network. So, rather than have people enter 192.168.1.1 or similar, they can just use that memorable domain name.

To establish an HTTPS connection, and avoid complaints from browsers about using insecure HTTP and untrusted certs, the router has to produce a valid HTTPS cert for routerlogin.net or routerlogin.com that is trusted by browsers. To cryptographically prove the cert is legit when a connection is established, the router needs to use the certificate’s private key. This key is stored unsecured in the firmware, allowing anyone to extract and abuse it.

Netgear doesn’t want to provide an HTTP-only admin interface, to avoid warnings from browsers of insecure connections and to thwart network eavesdroppers, we presume. But if it uses HTTPS, the built-in web server needs to prove its cert is legit, and thus needs its private key. So either Netgear switches to using per-device private-public keys, or stores the private key in a secure HSM in the router, or just uses HTTP, or it has to come up with some other solution. You can follow that debate here.

Source: Leave your admin interface’s TLS cert and private key in your router firmware in 2020? Just Netgear things • The Register