During DSA signature generation in the function `dsa_SignDigest`, the nonce value `k` is not padded, exposing the bit length of `k`, i.e. the most significant bits (MSBs) of the nonce. Combined with other techniques this can result in DSA private keys recovery.
OpenShift 4.x only packages nss-altfiles and has been confirmed to *not* share any of the vulnerable signature code:
- nss-altfiles only reads information from files in the same format as /etc/passwd and /etc/group.
Upstream patch: https://hg.mozilla.org/projects/nss/rev/daa823a4a29bcef0fec33a379ec83857429aea2e
Upstream bug (still private): https://bugzilla.mozilla.org/show_bug.cgi?id=1631576
Name: the Mozilla Project
Upstream: Cesar Pereida Garcia and the Network and Information Security Group (NISEC) (Tampere University)
Created nss tracking bugs for this issue:
Affects: fedora-all [bug 1838376]
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
@Huzaifa Can you clarify the mitigation statement? Is the mitigation not available or is it available and doesn't meet the Red Hat Product Security criteria. Is there any indication of when a mitigation would be available?
A timing attack was found in the way NSS generated DSA signatures. A man-in-the-middle attacker could use this attack during DSA signature generation to recover the private key. This attack is only feasible when the attacker is local to the machine or in certain cross-VM scenarios where the signature is being generated. Attacks over the network or via the internet are not feasible.
Firefox and Thunderbird on Red Hat Enterprise Linux are built against the system nss library.