A report released last week of a serious vulnerability affecting HTTPS servers and other services using the SSL version 2 (SSLv2), raises concerns about possible attacks that could expose encrypted communications.
Secure Sockets Layer (SSL) is a standard security technology that establishes an encrypted link between a server and a browser. An attack at this level could decrypt secure HTTPS communications, such as passwords or credit card numbers, within minutes. The flaw named DROWN, which stands for ‘Decrypting RSA with Obsolete and Weakened eNcryption’, affects some of the essential cryptographic protocols used in internet security.
Researchers behind the report estimate that more than 3.5 million HTTPS servers could be affected and victims could include anyone on the internet browsing the web, using email, shopping or sending instant messages. An attacker could strip encryption from the connection, allowing third parties to read the communication.
The team leading the investigation found that 38 percent of all HTTPS servers and 22 percent of those with browser-trusted certificates are vulnerable to the protocol-level attack. The attackers can gain any communication between users and the server, including usernames and passwords, credit card numbers, emails, instant messages and sensitive documents. Under some common scenarios, an attacker also can impersonate a secure website and intercept or change the content the user sees.
Unfortunately, individual computer users cannot do anything on their end to prevent becoming victims, as the attack would be at the server and website level and would need intervention at those points.
DROWN is a serious attack, but it can be prevented quite easily using measures that were recommended to server operators and system administrators a long time ago, according to Yehuda Lindell, chief scientist at digital security firm Dyadic. He added that the proper response to the attack is to disable SSLv2 everywhere, which can be complicated, and to also ensure that your private keys are not shared with any servers that use SSLv2.
SSLv2 goes back to 1995. It had several flaws, which was the main reason SSLv3 was released in 1996. However, SSLv2 and SSLv3 were deprecated in 2011 and 2015 and should be disabled, regardless of the DROWN vulnerability.