Security and Privacy Considerations - w3c/webpayments GitHub Wiki
This page documents some security topics for consideration by the Web Payments Working Group. See also the WG's Security review using the TAG checklist.
Confidentiality Violations
Motivation: Attacker wants to know about victims location or spending behavior
Attack Vector: Browser extension or compromised Javascript code
Attacker installs code to listen to PaymentRequestUpdateEvents and report contents of PaymentDetails to attacker website.
Motivation: Merchant wants to know exactly which payment methods are available for a given consumer
Attack Vector: repeated calls to PaymentRequest interface with a single payment method per request; monitoring those which succeed and which fail
Attacker dispatches multiple PaymentRequest calls, capturing when a request fails immediately (which would be an indication the payment method is not supported) and otherwise aborting the PaymentRequest if it does not fail immediately. Collect the results and then through business logic decide which payment methods to offer to this customer. Remember the information via a cookie for future use. Offer new payment methods to the consumer because the merchant knows they do not yet have those methods registered and the merchant prefers those methods (e.g., private card, card with loyalty points, card with better terms for the merchant).
Password Sniffing
No known password sniffing attacks
Offline Cryptographic Attacks
No known cryptographic attacks other than capture and brute force HTTPS.
Replay Attacks
Motivation: MitM wants to harm merchant by issuing previously processed PaymentResponses
Attack Vector: Browser extension or compromised Javascript code
Attacker installs code that store (via localStorage) and replay previous basic card spec payment responses.
Message Insertion
Motivation: MitM wants to mine victim data by requesting fields that merchant does not need.
Attack Vector: Browser extension or compromised Javascript code
Attacker installs code that modifies paymentOptions to request information that merchant does not need and then reports this back to attacker's servers.
Message Deletion
Motivation: MitM wants to reprioritize acceptable payment methods.
Attack Vector: Browser extension or compromised Javascript code
Attacker installs code that modifies the list of acceptable payment methods before sending them on to the mediator.
Message Modification
Motivation: MitM wants to harm merchant by modifying price charged by merchant.
Attack Vector: Browser extension or compromised Javascript code
Attacker installs code that modifies total amount displayed to user and then modifies the amount before it is sent to the mediator.