Look up a file hash (MD5/SHA1/SHA256) against MalwareBazaar and VirusTotal. Returns malware family, detection stats, and file metadata. Args: hash_str: MD5 (32 hex), SHA1 (40 hex), or SHA256 (64 hex) hash
AI agents call lookup_file_hash to retrieve information from CVE MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and queries threat intelligence data from external services (MalwareBazaar and VirusTotal) based on a file hash input. It performs no modifications, deletions, code execution, or financial operations. It is a read-only intelligence gathering function with minimal blast radius if misused—an agent might receive false positive malware information but cannot cause damage through this tool alone.
From the tool's definition The tool 'Look up a file hash' against MalwareBazaar and VirusTotal 'Returns malware family, detection stats, and file metadata.' This is purely a query/lookup operation with no side effects.
Documented attack patterns abuse exactly the kind of access lookup_file_hash gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and CVE MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for lookup_file_hash:
{
"version": "1",
"default": "deny",
"tools": {
"lookup_file_hash": {}
}
}lookup_file_hash is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Look up a file hash (MD5/SHA1/SHA256) against MalwareBazaar and VirusTotal. Returns malware family, detection stats, and file metadata. Args: hash_str: MD5 (32 hex), SHA1 (40 hex), or SHA256 (64 hex) hash. It is categorised as a Read tool in the CVE MCP Server MCP Server, which means it retrieves data without modifying state.
Register the CVE MCP Server MCP server in PolicyLayer and add a rule for lookup_file_hash: 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 CVE MCP Server. Nothing to install.
lookup_file_hash is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the lookup_file_hash 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 lookup_file_hash. 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.
lookup_file_hash is provided by the CVE MCP Server MCP server (mukul975/cve-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from CVE MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
27 CVE MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.