MISP: Site-Admin Can Repoint Redis Workers to Attacker-Controlled Server via UI/API Configuration Change

MISP exposes critical infrastructure settings—specifically the Redis host addresses used by the core application, the ZeroMQ plugin, and the SimpleBackgroundJobs plugin—through its web UI and API to site-admin users. The background job workers trust raw Redis job payloads without additional validation. An attacker who obtains a hijacked site-admin session (for example, through a stored cross-site scripting vulnerability) can modify the Redis host settings to point at an attacker-controlled Redis server and then restart the workers. Once the workers connect to the attacker's Redis instance, the attacker can inject malicious job payloads that the workers execute, achieving arbitrary command execution as the worker account. Additionally, the download_attachments_on_load setting, which controls inline attachment rendering, was modifiable through the same interface, allowing a hijacked session to re-enable a feature that could facilitate further client-side attacks. The vulnerability requires site-admin privileges and a prior session-compromise mechanism; it does not require unauthenticated access. The impact is remote code execution in the context of the MISP worker process and potential data exfiltration through the attacker-controlled Redis connection.