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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2019.0731 ChaCha20-Poly1305 with long nonces (CVE-2019-1543) 8 March 2019 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: OpenSSL 1.1.1 OpenSSL 1.1.0 Publisher: OpenSSL Operating System: Windows UNIX variants (UNIX, Linux, OSX) Impact/Access: Overwrite Arbitrary Files -- Remote with User Interaction Access Confidential Data -- Remote with User Interaction Reduced Security -- Remote with User Interaction Resolution: Patch/Upgrade CVE Names: CVE-2019-1543 Original Bulletin: https://www.openssl.org/news/secadv/20190306.txt Comment: OpenSSL 1.0.2 and 1.1.0 are currently only receiving security updates. Support for 1.0.2 will end on 31st December 2019. Support for 1.1.0 will end on 11th September 2019. Users of these versions should upgrade to OpenSSL 1.1.1. - --------------------------BEGIN INCLUDED TEXT-------------------- OpenSSL Security Advisory [6 March 2019] ======================================== ChaCha20-Poly1305 with long nonces (CVE-2019-1543) ================================================== Severity: Low 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. OpenSSL versions 1.1.1 and 1.1.0 are affected by this issue. Due to the limited scope of affected deployments this has been assessed as low severity and therefore we are not creating new releases at this time. The 1.1.1 mitigation for this issue can be found in commit f426625b6a. The 1.1.0 mitigation for this issue can be found in commit ee22257b14. This issue does not impact OpenSSL 1.0.2. This issue was discovered by Joran Dirk Greef of Ronomon. The fix was developed by Matt Caswell from the OpenSSL development team. It was reported to OpenSSL on 26th February 2019. Note ==== OpenSSL 1.0.2 and 1.1.0 are currently only receiving security updates. Support for 1.0.2 will end on 31st December 2019. Support for 1.1.0 will end on 11th September 2019. Users of these versions should upgrade to OpenSSL 1.1.1. References ========== URL for this Security Advisory: https://www.openssl.org/news/secadv/20190306.txt Note: the online version of the advisory may be updated with additional details over time. For details of OpenSSL severity classifications please see: https://www.openssl.org/policies/secpolicy.html - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBXIHI5maOgq3Tt24GAQganhAAxkBHjmWW7ECABhToZi4UzgzGuIWyeO9o RBHvUCYnFiBRO7vQ1kG9QNqD0fL29kG+ccaY2lZ6bjSqP7lzTGM1oj5/4c+B2f9J 0bpFWoJBL/8K0Or1MYEbU8EJ2cuP1DXr/KgEQdgtb8jmq/h7BMayIgLLJB1kOi5G 7+j+YGemFx6WpiF3dxp/iT/+ca14K6GHM0yzRYrgaMWkNbMmzZrQGzr347xzWsDm QEIaDyKwxyUCgdJC0XX5snrwWDPA5ODw2kaUEMcpe+UQnIxYmfKdOiqo7ud3B1kC OsGAaxX/FCt/N5dEVMaAQp9irqc8aT7uTugO6QSTrQL7B7oL/f5vMozoxA4abqp9 wKB9XhnQItx0yHYvYyRhONt4e5soaoxYZ8HH4UMrOhqVyJFJFUqznBPZso4P7aje PEtsPF8eAIpAxdmI6mqYuVAkBoOes9WJCkWhvrfzFn8PE7DiZh9NQwfE/7d7/3cQ TraFhacMF84r9jPeJl1f+lsdmHsVdGQGln+b20KlTfe0mHmXgZ4qFaO57sIkC1YC 929sxSuCf0WjA2BpErpnCLtlwwW1TsYumDYzm+j5OnpwIixkd9/bfZBQRVKooft/ LeOLk1C8U8ugAGuhCKqQA4gBGDksAiuzlKdRUErh2U1CPwzlTx6E6z4KgszcgNUk aLvvChDX1wQ= =/rrU -----END PGP SIGNATURE-----