SB2019011002 - Ubuntu update for NSS

Description

This security bulletin contains information about 3 secuirty vulnerabilities.

1) Memory-cache side-channel attack (CVE-ID: CVE-2018-0495)

The vulnerability allows a local attacker to obtain potentially sensitive information.

The vulnerability exists due to a leakage of information through memory caches when the affected library uses a private key to create Elliptic Curve Digital Signature Algorithm (ECDSA) signatures.  A local attacker can conduct a memory-cache side-channel attack on ECDSA signatures and recover sensitive information, such as ECDSA private keys, which could be used to conduct further attacks. 

Note: The vulnerability is known as the "Return Of the Hidden Number Problem" or ROHNP.

2) Man-in-the-middle attack (CVE-ID: CVE-2018-12384)

The vulnerability allows a remote attacker to conduct man-in-the-middle attack on the target system.

The weakness exists due to ServerHello.random is all zero when handling a v2-compatible ClientHello. A remote attacker can use man-in-the-middle techniques to conduct passive replay attack and obtain potentially sensitive information.

3) Cache Attacks (CVE-ID: CVE-2018-12404)

The vulnerability allows a remote attacker to perform a downgrade attack on the server and decrypt private keys on the target system.

The vulnerability exists due to a core weakness in TLS that relates to the handshaking of the session key which is used within the tunnel during parallelisation of thousands of oracle queries that occurs using a cluster of TLS servers which share the same public key certificate. A remote attacker can mount a microarchitectural side channel attack against a vulnerable implementation, obtain a network man-in-the-middle position, obtain the relevant data to sign and trigger the victim server to decrypt ciphertexts chosen by the adversary to perform a downgrade attack.

Remediation

Install update from vendor's website.

References

• https://usn.ubuntu.com/3850-1/