Bleichenbacher style attack in wolfSSL

1) Use of a broken or risky cryptographic algorithm

EUVDB-ID: #VU84838

Risk: Medium

CVSSv3.1: 4.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: N/A

CWE-ID: CWE-327 - Use of a Broken or Risky Cryptographic Algorithm

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to sensitive information.

The vulnerability exists due to usage of weak cryptographic ciphers susceptible to a Bleichenbacher style attack. A remote attacker can decrypt a saved TLS connection and potentially forge a signature after probing with a large number of trial connections.

Note, this issue is around RSA decryption and affects static RSA cipher suites on the server side, which are not recommended to be used and are off by default.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

wolfSSL: 5.0.0 - 5.6.3

External links

http://github.com/wolfSSL/wolfssl/releases/tag/v5.6.4-stable
http://github.com/wolfSSL/wolfssl/pull/6896

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.