Indian firm's compromised TLS keys put websites at risk
What's the story
Cybersecurity experts are sounding alarms after the discovery of eight weak Transport Layer Security (TLS) certificates. The private keys associated with these certificates are so weak that they could be exploited by anyone to create trusted browser and app credentials for any website on the internet. The threat is particularly concerning as it could potentially undermine the trustworthiness of online communications and transactions.
Immediate action
Immediate action taken by browser makers
In response to the discovery of these compromised TLS certificates, browser makers and some major apps and programming languages have taken immediate action. They have blocked all eight of the intermediate certificates.
However, despite this swift response, there are still concerns over other key parts of the internet such as Linux distributions and Internet of Things (IoT) devices that remain vulnerable.
Certificate authority
Certificates were issued by India-based eMudhra
The eight compromised intermediate certificates were issued by India-based certificate authority eMudhra Limited.
An informal advisory posted on emudhra.we-have-a-problem.com read, "We have a problem here - Wayne."
This message was digitally signed with one of the private keys from the eMudhra certificates, proving that the reporting party had control over it and could use it to sign unauthorized certificates trusted by millions of servers worldwide.
Cleanup challenge
Cleanup job bigger than Heartbleed
Filippo Valsorda, a cryptography engineer and maintainer of the open-source Go programming language, warned that this incident could lead to a cleanup job bigger than Heartbleed, the huge 2014 internet security crisis.
He said it would take a long time to update all affected systems, including IoT devices and unmaintained Linux machines.
Valsorda also noted that some Linux distributions are still rolling out updates, which adds another layer of complexity to the situation.
Key concerns
Compromised keys had only 3-8 bits of entropy
The compromised eMudhra keys had entropy levels that are hard to comprehend for many engineers looking into the case.
A normal NIST P-384 elliptic curve cryptography private key has some 384 bits of entropy, allowing almost 2^384 different possibilities.
However, the sizes of the compromised keys ranged from just 3-8 bits.
This anomaly has led some experts to speculate about a possible flaw in key generation interface or accidental leak of example code to production.
VPN vulnerability
Immediate threat for VPN users
The immediate threat from the compromised certificates seems to be for those using VPNs, particularly in countries where governments are likely to intercept traffic maliciously.
However, most browsers have already blocked the intermediate certificates.
The only exception is Edge on Windows 10, which was still connecting to 12 vulnerable hosts at the time of writing, as per Arstechnica.