Vulnerability · Published Jan 25, 2022 · Assigned by GitHub_M
CVE-2021-43799RabbitMQ exposes ports with weak default secrets in Zulip Server
High 8.6
In plain English
A high-severity security flaw in zulip from zulip. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 5.4% (higher than 93% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Official description
Zulip is an open-source team collaboration tool. Zulip Server installs RabbitMQ for internal message passing. In versions of Zulip Server prior to 4.9, the initial installation (until first reboot, or restart of RabbitMQ) does not successfully limit the default ports which RabbitMQ opens; this includes port 25672, the RabbitMQ distribution port, which is used as a management port. RabbitMQ's default "cookie" which protects this port is generated using a weak PRNG, which limits the entropy of the password to at most 36 bits; in practicality, the seed for the randomizer is biased, resulting in approximately 20 bits of entropy. If other firewalls (at the OS or network level) do not protect port 25672, a remote attacker can brute-force the 20 bits of entropy in the "cookie" and leverage it for arbitrary execution of code as the rabbitmq user. They can also read all data which is sent through RabbitMQ, which includes all message traffic sent by users. Version 4.9 contains a patch for this vulnerability. As a workaround, ensure that firewalls prevent access to ports 5672 and 25672 from outside the Zulip server.
Affected products (as reported)
Weakness: CWE-338 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
References
- https://github.com/zulip/zulip/security/advisories/GHSA-p663-wxvv-2fjp x_refsource_CONFIRM
- https://github.com/zulip/zulip/commit/a5496f4098e3998c9b84e8dc564aa983d6cdf6e8 x_refsource_MISC
- https://github.com/gteissier/erl-matter x_refsource_MISC
- https://github.com/zulip/zulip/releases/tag/4.9 x_refsource_MISC