An OpenSSL vulnerability patched in early May with the release of versions 1.0.2h and 1.0.1t still hasn’t been patched on many of the world’s most visited websites, exposing potentially sensitive traffic to man-in-the-middle (MitM) attacks.
Last week, security firm High-Tech Bridge used its free SSL/TLS testing service to determine how many of the Alexa Top 10,000 websites are still plagued by the OpenSSL vulnerability tracked as CVE-2016-2107.
The flaw was introduced in 2013 as part of the fix for the TLS attack dubbed “Lucky 13.” In April, Juraj Somorovsky discovered that an MitM attacker can launch a padding oracle attack to decrypt traffic in cases where the connection uses an AES CBC cipher and the server supports AES-NI instructions.
“The bad news is that support of the AES CBC cipher is widely recommended for compatibility reasons, required by TLS 1.2 RFC and recommended by NIST guidelines. AES CBC cipher is also considered the strongest cipher for TLS 1.0 and TLS 1.1,” the security firm said in a blog post.
High-Tech Bridge told SecurityWeek that it conducted an automated, non-intrusive scan of the Alexa Top 10,000 websites by looking for the use of AES CBC and by using custom OpenSSL code specially designed to check for the existence of CVE-2016-2107.
The scan revealed that either web or email servers associated with 1,829 (19.29 percent) of the top websites had been both vulnerable and exploitable. Researchers determined that 62 percent of servers (6,258) were not vulnerable, and 19 percent (1,913) were vulnerable, but not exploitable.
“Taking into consideration that the vulnerability can be exploited in practice and allows stealing user data, credentials, financial and personal information, such results are pretty disappointing,” researchers noted.
Companies that want to determine if their web or email server is vulnerable can use the security firm’s free SSL/TLS testing service.
Related: Non-Security OpenSSL Bugs Lead to Serious Vulnerability