GHSA-4jqp-9qjv-57m2

Description

### Impact The Keylime registrar does not enforce mutual TLS (mTLS) client certificate authentication since version 7.12.0. The registrar's TLS context is configured with `ssl.CERT_OPTIONAL` instead of `ssl.CERT_REQUIRED`, allowing any client to connect to protected API endpoints without presenting a valid client certificate. **Who is impacted:** - All Keylime deployments running versions 7.12.0 through 7.13.0 - Environments where the registrar HTTPS port (default 8891) is network-accessible to untrusted clients **What an attacker can do:** - **List all registered agents** (`GET /v2/agents/`) - enumerate the entire agent inventory - **Retrieve agent details** (`GET /v2/agents/{uuid}`) - obtain public TPM keys, certificates, and network locations (IP/port) of any agent - **Delete any agent** (`DELETE /v2/agents/{uuid}`) - remove agents from the registry, disrupting attestation services Note: The exposed TPM data (EK, AK, certificates) consists of public keys and certificates. Private keys remain protected within TPM hardware. The HMAC secret used for challenge-response validation is stored in the database but is not exposed via the API. **Affected versions:** >= 7.12.0, <= 7.13.0 **Fixed versions:** 7.12.2, >= 7.13.1 ### Patches A patch for the affected released versions is available. It removes the line that override the configuration of `ssl.verify_mode`, leaving the `CERT_REQUIRED` value set by `web_util.init_mtls()`: ```diff diff --git a/keylime/web/base/server.py b/keylime/web/base/server.py index 1d9a9c2..859b23a 100644 --- a/keylime/web/base/server.py +++ b/keylime/web/base/server.py @@ -2,7 +2,6 @@ import asyncio import multiprocessing from abc import ABC, abstractmethod from functools import wraps -from ssl import CERT_OPTIONAL from typing import TYPE_CHECKING, Any, Callable, Optional import tornado @@ -252,7 +251,6 @@ class Server(ABC): self._https_port = config.getint(component, "tls_port", fallback=0) self._max_upload_size = config.getint(component, "max_upload_size", fallback=104857600) self._ssl_ctx = web_util.init_mtls(component) - self._ssl_ctx.verify_mode = CERT_OPTIONAL def _get(self, pattern: str, controller: type["Controller"], action: str, allow_insecure: bool = False) -> None: """Creates a new route to handle incoming GET requests issued for paths which match the given ``` Users should upgrade to the patched version once it is released. ### Workarounds If upgrading is not immediately possible, apply one of the following mitigations: #### 1. Network isolation (Recommended) Restrict access to the registrar HTTPS port (default 8891) using firewall rules to allow only trusted hosts (verifier, tenant): ##### Example using iptables ``` iptables -A INPUT -p tcp --dport 8891 -s <verifier_ip> -j ACCEPT iptables -A INPUT -p tcp --dport 8891 -s <tenant_ip> -j ACCEPT iptables -A INPUT -p tcp --dport 8891 -j DROP ``` #### 2. Reverse proxy with mTLS enforcement Deploy a reverse proxy (nginx, HAProxy) in front of the registrar that enforces client certificate authentication: ##### Example nginx configuration ``` server { listen 8891 ssl; ssl_certificate /path/to/server.crt; ssl_certificate_key /path/to/server.key; ssl_client_certificate /path/to/ca.crt; ssl_verify_client on; # Enforce client certificates location / { proxy_pass https://localhost:8892; # Internal registrar port } } ```