AI agents use upload_file to create or update resources in YaraFlux MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your YaraFlux MCP Server environment.
The tool creates or writes files to the server's storage system, making it a Write operation. Severity is medium because malicious file uploads could introduce threats into the analysis system, consume storage, or be used in combination with YARA rules to craft evasive malware, but the tool itself doesn't delete data (Destructive) or execute arbitrary code (Execute).
From the tool's definition Tool name 'upload_file' indicates file creation/storage operation. Combined with sibling tools 'download_file', 'delete_file', and 'clean_storage', this server manages a file storage system. Upload operations create or add files to the system.
Documented attack patterns abuse exactly the kind of access upload_file gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and YaraFlux MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for upload_file:
{
"version": "1",
"default": "deny",
"tools": {
"upload_file": {
"limits": [
{
"counter": "upload_file_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}upload_file 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.
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upload_file. It is categorised as a Write tool in the YaraFlux MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the YaraFlux MCP Server MCP server in PolicyLayer and add a rule for upload_file: 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 YaraFlux MCP Server. Nothing to install.
upload_file 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 upload_file 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 upload_file. 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.
upload_file is provided by the YaraFlux MCP Server MCP server (threatflux/yaraflux). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from YaraFlux MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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20 YaraFlux MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.