Remote denial of service during Encrypt-Then-Mac renegotiation in OpenSSL

1) Improper input validation

EUVDB-ID: #VU5839

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2017-3733

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to cause denial of service.

The vulnerability exists due to improper input validation during a renegotiation handshake, if the Encrypt-Then-Mac extension is negotiated where it was not in the original handshake. A remote attacker can send a specially crafted data to vulnerable application and case denial of service conditions.

Successful exploitation of the vulnerability may result in denial of service (DoS) attack.

Mitigation

Update to version 1.1.0e.

Vulnerable software versions

OpenSSL: 1.1.0 - 1.1.0d

CPE2.3

• cpe:2.3:a:openssl_software_foundation:openssl:1.1.0:*:*:*:*:*:*:*
• cpe:2.3:a:openssl_software_foundation:openssl:1.1.0a:*:*:*:*:*:*:*
• cpe:2.3:a:openssl_software_foundation:openssl:1.1.0b:*:*:*:*:*:*:*
• cpe:2.3:a:openssl_software_foundation:openssl:1.1.0c:*:*:*:*:*:*:*
• cpe:2.3:a:openssl_software_foundation:openssl:1.1.0d:*:*:*:*:*:*:*

External links

https://www.openssl.org/news/secadv/20170216.txt

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.