On Monday, April 7th, 2014, a major security vulnerability in OpenSSL was made public. The vulnerability was filed as CVE-2014-0160 and later dubbed “Heartbleed”, because the bug lies within OpenSSL’s heartbeat extension, which is used for keepalive monitoring. As a result of the bug, process memory can be read out remotely by an attacker—potentially including certificates, keys, credentials, tokens, or other sensitive data processed by the server.
OpenSSL works as a cryptographic library that allows for authenticity and confidentiality across the entire Internet. Because the reported Heartbleed bug affects a vast number of internet services using OpenSSL to secure their services (such as HTTPS, SMTP, IMAPS, and POP3), a patched OpenSSL version was released by the maintainers within hours. Linux and UNIX distributions, which depend on the OpenSSL implementation, received patches by their respective upstream maintainers.
SoundCloud too uses OpenSSL in many of our services to increase the security and privacy of our users. We therefore moved quickly to patch the vulnerability, and did so within hours of the patch being made available. We’ve also been in close communications with our vendors and service providers, to ensure that they have applied the appropriate fixes as well. We have confirmed that our implementations of OpenSSL are no longer vulnerable to this bug.
Because we consider our users’ security and privacy of the utmost importance, we have further taken the precautionary measures to rotate SSL certificates and keys, and expire authentication tokens, such as session cookies, remember tokens, and OAuth access and refresh tokens. This means that users will be signed out of their SoundCloud accounts. Along with top security researchers and responsible companies, we have also recommended to our users that they change their passwords on all accounts (not just SoundCloud) that they have signed-in with in the past week. Developers of API clients that check our SSL fingerprints will need to update them.
While the Heartbleed bug marks a sad day for the Internet as a whole, with SoundCloud’s rollout of Perfect Forward Secrecy (PFS) support last year, we ensured that the impact of an attack with the purpose of stealing private keys and reading previously encrypted traffic is minimized. In the same spirit we will also strive to find more such opportunities in the future and preemptively provide our users with the highest possible level of safety.