snow_file_upload
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.
This record as markdown: /tools/serac/snow-file-upload.md
What snow_file_upload does on Serac
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.
Why snow_file_upload is rated Medium
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
The rule that runs snow_file_upload safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Serac, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For snow_file_upload, this is the rule to start with:
snow_file_upload stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Serac, apply this rule, and every snow_file_upload call is checked against it from then on.
Questions about snow_file_upload
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.
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