GHSA-46q5-g3j9-wx5c

ZeptoClaw: Generic webhook channel trusts caller-supplied identity fields; allowlist is checked against untrusted payload data

### Summary The generic webhook channel trusts caller-supplied identity fields (`sender`, `chat_id`) from the request body and applies authorization checks to those untrusted values. Because authentication is optional and defaults to disabled (`auth_token: None`), an attacker who can reach `POST /webhook` can spoof an allowlisted sender and choose arbitrary `chat_id` values, enabling high-risk message spoofing and potential IDOR-style session/chat routing abuse. ### Details Relevant code paths: - `src/channels/webhook.rs:121` sets runtime default `auth_token: None`. - `src/config/types.rs:910` also defaults webhook config `auth_token` to `None`. - `src/channels/webhook.rs:224` (`validate_auth`) explicitly allows requests when no token is configured. - `src/channels/webhook.rs:128` defines `WebhookPayload` with identity fields fully controlled by caller input: - `sender: String` - `chat_id: String` - `src/channels/webhook.rs:421` performs allowlist authorization using `payload.sender`. - `src/channels/webhook.rs:433` and `src/channels/webhook.rs:434` create `InboundMessage` using untrusted `payload.sender` and `payload.chat_id`. Why this is vulnerable: - The system treats user-provided JSON identity as authoritative identity. - Allowlist enforcement does not verify sender authenticity beyond that payload value. - `chat_id` is also attacker-controlled, so routing/session association can be steered to arbitrary chats/conversations. - If the webhook is exposed without strong upstream authn/authz controls, spoofing is straightforward. ### PoC 1. Configure the webhook channel in a vulnerable posture (common default behavior): - `enabled = true` - `bind_address = "0.0.0.0"` (or any reachable interface) - `port = 9876` - `path = "/webhook"` - `auth_token = null` (or omitted) - `allow_from = ["trusted-user-1"]` - `deny_by_default = true` 2. Start ZeptoClaw. 3. Send a forged request with attacker-chosen `sender` and `chat_id`, without any `Authorization` header: ```bash curl -i -X POST "http://127.0.0.1:9876/webhook" \ -H "Content-Type: application/json" \ --data '{ "message":"FORGED: run privileged workflow", "sender":"trusted-user-1", "chat_id":"victim-chat-42" }' ``` 4. Observe: - Response is `HTTP/1.1 200 OK`. - Message is accepted as if it originated from `trusted-user-1`. - Message is routed under attacker-chosen `chat_id` (`victim-chat-42`). ### Impact - Vulnerability type: - Authentication/authorization bypass (identity spoofing) - IDOR-style routing/control issue via attacker-chosen `chat_id` - Affected deployments: - Any deployment exposing the generic webhook endpoint without strict upstream authentication and identity binding. - Security consequences: - Forged inbound messages from spoofed trusted users. - Bypass of allowlist intent by injecting allowlisted sender IDs in payload. - Cross-chat/session contamination or hijacking by choosing arbitrary `chat_id`. - Potential unauthorized downstream agent/tool actions triggered by malicious input.