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FreeBSD : Mbed TLS -- Side channel attack on deterministic ECDSA (1c948fd3-dac0-11e9-81b2-0011d823eebd)

high Nessus Plugin ID 129084

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Synopsis

The remote FreeBSD host is missing a security-related update.

Description

Janos Follath reports :

Mbed TLS does not have a constant-time/constant-trace arithmetic library and uses blinding to protect against side channel attacks.

In the ECDSA signature routine previous Mbed TLS versions used the same RNG object for generating the ephemeral key pair and for generating the blinding values. The deterministic ECDSA function reused this by passing the RNG object created from the private key and the message to be signed as prescribed by RFC 6979. This meant that the same RNG object was used whenever the same message was signed, rendering the blinding ineffective.

If the victim can be tricked to sign the same message repeatedly, the private key may be recoverable through side channels.

Solution

Update the affected package.

See Also

http://www.nessus.org/u?91a12f0c

http://www.nessus.org/u?d88c040d

Plugin Details

Severity: High

ID: 129084

File Name: freebsd_pkg_1c948fd3dac011e981b20011d823eebd.nasl

Version: 1.1

Type: local

Published: 9/20/2019

Updated: 9/20/2019

Supported Sensors: Nessus

Vulnerability Information

CPE: p-cpe:/a:freebsd:freebsd:mbedtls, cpe:/o:freebsd:freebsd

Required KB Items: Host/local_checks_enabled, Host/FreeBSD/release, Host/FreeBSD/pkg_info

Patch Publication Date: 9/19/2019

Vulnerability Publication Date: 9/6/2019