AI agents use snow_event_handler to create or update resources in Serac — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Serac environment.
This tool creates a new event handler record (sysevent_script_action) in ServiceNow, which is a Write operation. However, it has high severity because registering arbitrary script actions that execute on platform events can have broad systemic effects — any time the named event fires, the registered script will run, potentially affecting many records, processes, or integrations across the platform.
From the tool's definition Register a script action (sysevent_script_action) that runs when a named platform event fires
Attacks that exploit this kind of access
Register a script action (sysevent_script_action) that runs when a named platform event fires. Script must be ES5-compatible (no arrow functions, const/let, etc.). It is categorised as a Write tool in the Serac MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Serac MCP server in PolicyLayer and add a rule for snow_event_handler: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Serac. Nothing to install.
snow_event_handler is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the snow_event_handler rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for snow_event_handler. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
snow_event_handler is provided by the Serac MCP server (serac-labs/serac). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
snow_event_handler is one line of Serac's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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