Test ID:	1.3.6.1.4.1.25623.1.0.108610
Category:	General
Title:	OpenSSL: ChaCha20-Poly1305 with long nonces (CVE-2019-1543) - Linux
Summary:	OpenSSL is prone to a vulnerability which allows a nonce reuse.
Description:	Summary: OpenSSL is prone to a vulnerability which allows a nonce reuse. Vulnerability Insight: ChaCha20-Poly1305 is an AEAD cipher, and requires a unique nonce input for every encryption operation. RFC 7539 specifies that the nonce value (IV) should be 96 bits (12 bytes). OpenSSL allows a variable nonce length and front pads the nonce with 0 bytes if it is less than 12 bytes. However it also incorrectly allows a nonce to be set of up to 16 bytes. In this case only the last 12 bytes are significant and any additional leading bytes are ignored. It is a requirement of using this cipher that nonce values are unique. Messages encrypted using a reused nonce value are susceptible to serious confidentiality and integrity attacks. If an application changes the default nonce length to be longer than 12 bytes and then makes a change to the leading bytes of the nonce expecting the new value to be a new unique nonce then such an application could inadvertently encrypt messages with a reused nonce. Additionally the ignored bytes in a long nonce are not covered by the integrity guarantee of this cipher. Any application that relies on the integrity of these ignored leading bytes of a long nonce may be further affected. Any OpenSSL internal use of this cipher, including in SSL/TLS, is safe because no such use sets such a long nonce value. However user applications that use this cipher directly and set a non-default nonce length to be longer than 12 bytes may be vulnerable. Affected Software/OS: OpenSSL versions 1.1.1 up to and including 1.1.1b and 1.1.0 up to and including 1.1.0j. This issue does not impact OpenSSL 1.0.2. Solution: Upgrade OpenSSL to version 1.1.0k, 1.1.1c or later. See the references for more details. CVSS Score: 5.8 CVSS Vector: AV:N/AC:M/Au:N/C:P/I:P/A:N
Cross-Ref:	Common Vulnerability Exposure (CVE) ID: CVE-2019-1543 Bugtraq: 20190701 [SECURITY] [DSA 4475-1] openssl security update (Google Search) https://seclists.org/bugtraq/2019/Jul/3 Debian Security Information: DSA-4475 (Google Search) https://www.debian.org/security/2019/dsa-4475 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZBEV5QGDRFUZDMNECFXUSN5FMYOZDE4V/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/Y3IVFGSERAZLNJCK35TEM2R4726XIH3Z/ https://www.oracle.com/security-alerts/cpuapr2020.html https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html RedHat Security Advisories: RHSA-2019:3700 https://access.redhat.com/errata/RHSA-2019:3700 SuSE Security Announcement: openSUSE-SU-2019:1814 (Google Search) http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00056.html
Copyright	Copyright (C) 2019 Greenbone AG

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