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العربيةPublicly writable EventBridge bus
An EventBridge bus policy grants Principal:* (public PutEvents)..
No IAM permission is needed. The exposure is in the resource's own configuration, so anyone the policy names, or everyone when it is public, can reach it.
This is a configuration exposure, not a permission. An EventBridge bus policy grants Principal:* (public PutEvents). Anyone the policy allows, or everyone when it is public, can reach it with no IAM access of their own.
Why it is dangerous
An EventBridge bus accepts events from anyone; an attacker can inject events into the account's automation.
In MITRE ATT&CK terms this maps to T1190, Exploit Public-Facing Application, under the initial access tactic.
Detection
Prerequisites
None beyond holding the permission.
MITRE ATT&CK
T1190 · Exploit Public-Facing ApplicationTactic
Initial Access
A control that would remove it: Remove the public statement from the event-bus policy (events:RemovePermission).
Whether to apply it depends on how the permission is used in your environment, so it is a business decision rather than an automatic fix. The same permission can be load-bearing in one account and pure risk in another.
Pathbreak confirms whether this path resolves in your account, ranks it against the others by how much it opens up, and uses your threat model and business context to show which paths are worth cutting.
Questions
What does this configuration allow?
An EventBridge bus policy grants Principal:* (public PutEvents).
Does this need any IAM permission?
No. It is a configuration exposure. Anyone the resource policy names, or everyone when it is public, can reach it without holding any permission of their own.
How is publicly writable EventBridge bus detected?
Watch for the related CloudTrail management events.
How do you break this path?
A control that would remove it is: Remove the public statement from the event-bus policy (events:RemovePermission). Whether to apply it depends on how the permission is used in your account, so it is a business decision rather than an automatic fix.
Which MITRE ATT&CK technique is this?
T1190, Exploit Public-Facing Application, under the initial access tactic.
Related paths
Find this in your own account
We run a read-only scan of one AWS account and show you which of these paths exist, ranked by blast radius, with the change that breaks each one. First validated paths within the hour.