#VU5420 Out-of-bounds read in OpenSSL - CVE-2017-3731

Vulnerability identifier: #VU5420

Vulnerability risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2017-3731

CWE-ID: CWE-125

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
OpenSSL
Server applications / Encryption software

Vendor: OpenSSL Software Foundation

Description

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

The vulnerability exists due to out-of-bounds read in OpenSSL when processing truncated packets on 32-bit system using certain ciphers. A remote attacker can send a specially crafted truncated packet using CHACHA20/POLY1305 cipher for OpenSSL 1.1.0 or RC4-MD5 for 1.0.2 and trigger denial of service.

Successful exploitation of the vulnerability may allow an attacker to perform denial of service (DoS) attack against vulnerable system.

Mitigation
Update OpenSSL to version 1.0.2k or 1.1.0d.

Vulnerable software versions

OpenSSL: 1.0.2j - 1.0.2, 1.1.0c - 1.1.0

---

External links
https://www.openssl.org/news/secadv/20170126.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.