AI agents use add_yara_rule 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.
Adding a YARA rule creates or modifies security detection rules that could affect threat analysis behavior system-wide. This is reversible (rules can be deleted or updated), so it is Write rather than Destructive. However, malicious YARA rules could cause false positives/negatives in threat detection, creating medium severity.
From the tool's definition Tool name 'add_yara_rule' indicates creation or modification of YARA rule data. Sibling tools include 'delete_yara_rule' and other rule management functions, confirming this operates within a rule management system. No description provided.
Documented attack patterns abuse exactly the kind of access add_yara_rule 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 add_yara_rule:
{
"version": "1",
"default": "deny",
"tools": {
"add_yara_rule": {
"limits": [
{
"counter": "add_yara_rule_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_yara_rule 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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add_yara_rule. 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 add_yara_rule: 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.
add_yara_rule 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 add_yara_rule 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 add_yara_rule. 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.
add_yara_rule 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.
Free to start. No card required.
20 YaraFlux MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.