AI agents use snow_file_upload 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.
File upload is a Write operation: it creates new attachment records and modifies the target record's state by adding a linked resource. Severity is high because malicious file uploads could inject malware, scripts, or sensitive data into enterprise ServiceNow records, affecting multiple users and business processes.
From the tool's definition Tool uploads and attaches files to ServiceNow records (creates attachment data). Description explicitly states: 'Upload a base64-encoded file as an attachment on a specific record' — this is data creation/modification, not deletion or financial impact.
Attacks that exploit this kind of access
Upload a base64-encoded file as an attachment on a specific record (table + sys_id), with file name and MIME type. Equivalent to snow_upload_attachment — pick whichever fits your naming. 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_file_upload: 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_file_upload 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_file_upload 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_file_upload. 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_file_upload 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_file_upload 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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