Fix Logic Flow Bypass in Pyramid
Logic flow bypasses in Pyramid usually stem from improper state management across views. If you are relying on the client to 'pinky swear' they finished Step A before hitting Step B, you are getting pwned. This guide demonstrates how to enforce state transitions using server-side session tokens.
The Vulnerable Pattern
@view_config(route_name='checkout_final', renderer='json')
def checkout_final(request):
# VULNERABLE: No server-side check to see if payment (Step 2) was actually completed.
# An attacker can POST directly to this endpoint to trigger order fulfillment.
order_id = request.params.get('order_id')
fulfill_order(order_id)
return {'status': 'order_shipped'}The Secure Implementation
The vulnerability lies in trusting the request sequence implicitly. Attackers skip 'Step 2' (e.g., payment, validation) to trigger 'Step 3' (e.g., fulfillment). To fix this, implement a server-side state machine using Pyramid's signed sessions. Each view in a sensitive flow must verify a session flag set by the previous step. Once the flow is finished, clear the flags to prevent replay attacks. Never rely on the 'Referer' header or client-side hidden fields for flow control.
@view_config(route_name='checkout_final', renderer='json')
def checkout_final(request):
# SECURE: Verify the state machine via the session.
# The session is cryptographically signed in Pyramid, preventing client-side tampering.
if not request.session.get('payment_verified'):
return HTTPForbidden("Payment step not completed.")
order_id = request.params.get('order_id')
if order_id != request.session.get('active_order_id'):
return HTTPBadRequest("Order mismatch.")
fulfill_order(order_id)
# Clear state after completion to prevent replay
request.session.pop('payment_verified', None)
return {'status': 'order_shipped'}</code></pre>
Your Pyramid API
might be exposed to Logic Flow Bypass
74% of Pyramid apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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