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GHSA-6h3m-36w8-hv68
No affected components available
(This document is canonically: https://advisories.nats.io/CVE/CVE-2022-26652.txt)
Background
NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing.
JetStream is the optional RAFT-based resilient persistent feature of NATS.
Problem Description
The JetStream streams can be backed up and restored via NATS. The backup format is a tar archive file. Inadequate checks on the filenames within the archive file permit a so-called "Zip Slip" attack in the stream restore.
NATS nats-server through 2022-03-09 (fixed in release 2.7.4) did not correctly sanitize elements of the archive file, thus a user of NATS could cause the NATS server to write arbitrary content to an attacker-controlled filename.
Affected versions
NATS Server:
- 2.2.0 up to and including 2.7.3.
- Introduced with JetStream Restore functionality
- Fixed with nats-io/nats-server: 2.7.4
- Docker image: nats https://hub.docker.com/_/nats
- NB users of OS package files from our releases: a change in goreleaser defaults, discovered late in the release process, moved the install directory from /usr/local/bin to /usr/bin; we are evaluating the correct solution for subsequent releases, but not recutting this release.
NATS Streaming Server
- 0.15.0 up to and including 0.24.2
- Fixed with nats-io/nats-streaming-server: 0.24.3
- Embeds a nats-server, but this server is the old approach which JetStream replaces, so unlikely (but not impossible) to be configured with JS support
Workarounds
- Disable JetStream for untrusted users.
- If only one NATS account uses JetStream, such that cross-user attacks are not an issue, and any user in that account with access to the JetStream API is fully trusted anyway, then appropriate sandboxing techniques will prevent exploit.
- Eg, with systemd, the supplied util/nats-server-hardened.service example configuration demonstrates that NATS runs fine as an unprivileged user under ProtectSystem=strict and PrivateTmp=true restrictions; by only opening a ReadWritePaths hole for the JetStream storage area, the impact of this vulnerability is limited.
Solution
Upgrade the NATS server to at least 2.7.4.
We fully support the util/nats-server-hardened.service configuration for running a NATS server and encourage this approach.
Credits
This issue was reported (on 2022-03-07) to the NATS Maintainers by
Yiming Xiang, TIANJI LAB of NSFOCUS.
Thank you / 谢谢你！
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the integrity of the data.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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