Seth Grover

Malcolm's nginx based reverse proxy contains a URL path normalization inconsistency between its Lua based role-based access control (RBAC) authorization layer and nginx's own request routing logic. An authenticated user can craft a specially formatted request path to bypass role-based restrictions and reach administrative or role gated endpoints they should not have access to. This affects all restricted paths protected by the RBAC authorization layer, including file upload, PHP server, htadmin, and authentication management interfaces.

Malcolm's nginx Lua role-based access control (RBAC) layer decides whether an authenticated user may reach a role-restricted path (e.g. /htadmin, /auth, /admin login, /arkime/api/esadmin, NetBox, upload endpoints) by pattern-matching the raw, percent-encoded request URI. Nginx itself, however, selects which location block actually serves the request using the percent-decoded, normalized URI. Because the RBAC check never percent-decodes its input, an authenticated low-privilege user can request an admin-only path using percent-encoding (e.g. /%68tadmin.php) and have nginx route it to the restricted location while the Lua RBAC gate evaluating the un-decoded raw string finds no matching restriction and grants access.

Malcolm's upload-processing pipeline (scripts/safe-extract.py) enforces entry-count, nesting-depth, and total-uncompressed-byte limits when extracting container archives (zip/tar/rar/7z via libarchive), but those limits are not applied when the uploaded file is a single-stream compressed format (.gz, .bz2, .xz, .lzma, .lz) that isn't a .tar.*-style archive. Any authenticated user permitted to upload PCAP/log files can upload a small, highly compressible file (e.g. a gzip bomb) that decompresses to an effectively unbounded size on disk, exhausting the shared Docker volume used by OpenSearch, Logstash, Arkime, and Zeek, and disrupting the platform for all users.

Malcolm's front nginx reverse proxy defines a "Dashboards → Arkime shortcut" location using a case-insensitive regex matcher but a case-sensitive rewrite. A request whose path segment is not exact-lowercase (for example /IDDASH2ARK/...) enters the location (the matcher fires) but evades the rewrite (no redirect is issued), so nginx falls through to the location's proxy pass to the Arkime backend. That location is the one proxied location in the shipped config that does not include the per-location authentication file, so the request reaches Arkime unauthenticated. The same location also forwards a client-supplied X-Forwarded-User header un-overwritten, and Arkime is configured to trust X-Forwarded-User as the authenticated username — so an unauthenticated network caller can reach the Arkime backend while supplying a forged, auto-provisioned identity.

The Malcolm kiosk Flask application exposes a POST /script call/<script> endpoint with zero authentication and wildcard CORS (CORS(app)). An attacker can force the operator's browser to execute arbitrary management commands via CSRF, including control.py --wipe which permanently deletes all captured network traffic and forensic logs, or control.py --stop which blinds the security monitoring.

The Arkime live capture service (arkime-live) in Malcolm runs with network mode: host, exposing port 8005 on all network interfaces (viewHost=0.0.0.0). Arkime trusts the X-Forwarded-User header from any IP address (userAuthIps=::,0.0.0.0/0) and auto-creates users with full access. The passwordSecret is hardcoded to the public value "Malcolm". A network-adjacent attacker bypasses nginx entirely by connecting directly to port 8005 with a forged identity header.

Malcolm file-upload component ships the upstream FilePond PHP server (pqina/filepond-server-php) largely unmodified: Dockerfile copies all upstream *.php files and Malcolm only overwrites config.php and submit.php. Upstream index.php exposes a fetch API route that instructs the server to download an arbitrary URL with curl (including FOLLOWLOCATION) and, for HEAD requests, stores the fetched response body in the upload container's transfer directory and returns the transfer ID to the caller, enabling full readback of the fetched content.