Security experts have identified eight intermediate TLS certificates issued by the Indian certification authority eMudhra Limited that contain critically weak private keys. These vulnerabilities could have allowed attackers to generate fraudulent certificates and intercept secure traffic.
Developers of major browsers, applications, and programming languages have already blocked the compromised certificates. According to transparency logs, there is currently no evidence that these keys were exploited for malicious purposes.
The flaw stems from extremely low entropy in the private keys. While a NIST P-384 elliptic curve key should have 384 bits of entropy, the eMudhra keys were found to have simple integer values such as 4, 56, 66, 115, 155, 156, 230, and 237.
Mitigation efforts are expected to take years. While browsers have been updated, many legacy systems, including old Linux servers, Docker containers, and IoT devices, require manual updates to their root certificate stores to address the risk.
Microsoft has not yet released an update for the Edge browser on Windows 10, stating that they will provide further information when available. Security researchers noted that while the attack requires a man-in-the-middle setup, it is easier to execute within local networks.
