Logs a user in to WinCC using username and password. Stores the session credentials for subsequent requests. It is optional, because the MCP server could be started in the way that it is doing automatically a logon with the service account.
AI agents invoke login-user to trigger actions in WinCC V8 MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool authenticates a user and establishes a persistent session in a SCADA system. It triggers an external operation (authentication against WinCC) and stores session state that affects all subsequent requests. It is not a simple read — it creates a session context and has side effects on the server state.
From the tool's definition 'Logs a user in to WinCC using username and password. Stores the session credentials for subsequent requests.'
Documented attack patterns abuse exactly the kind of access login-user gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and WinCC V8 MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for login-user:
{
"version": "1",
"default": "deny",
"tools": {
"login-user": {
"limits": [
{
"counter": "login-user_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}login-user stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Logs a user in to WinCC using username and password. Stores the session credentials for subsequent requests. It is optional, because the MCP server could be started in the way that it is doing automatically a logon with the service account. It is categorised as a Execute tool in the WinCC V8 MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the WinCC V8 MCP Server MCP server in PolicyLayer and add a rule for login-user: 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 WinCC V8 MCP Server. Nothing to install.
login-user is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the login-user 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 login-user. 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.
login-user is provided by the WinCC V8 MCP Server MCP server (vogler75/winccv8-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from WinCC V8 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.
38 WinCC V8 MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.