CVE-2004-1209 in Payflow Link
Summary
by MITRE
Verisign Payflow Link, when running with empty Accepted URL fields, does not properly verify the data in the hidden AMOUNT field, which allows remote attackers to modify the price of the items that they purchase.
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Analysis
by VulDB Data Team • 07/21/2017
The vulnerability described in CVE-2004-1209 affects Verisign Payflow Link, a payment processing system that facilitates online transactions between merchants and customers. This flaw represents a critical security weakness in the payment validation mechanism, specifically targeting the integrity verification of transaction amounts. The vulnerability arises from improper input validation within the payment processing pipeline, where the system fails to adequately validate the AMOUNT field when the Accepted URL fields are empty. This creates a scenario where malicious actors can manipulate transaction values without proper authorization, fundamentally compromising the financial integrity of the payment process.
The technical implementation of this vulnerability stems from a lack of proper data validation controls within the Payflow Link system. When the Accepted URL fields are empty, the system should enforce strict validation of all transaction parameters including the AMOUNT field. However, the system fails to implement adequate checks, allowing attackers to inject modified values into the hidden AMOUNT field. This represents a classic case of insufficient input sanitization and validation, which can be categorized under CWE-20 - Improper Input Validation. The vulnerability exists at the application layer where transaction data is processed and validated, creating a path for attackers to manipulate payment values through manipulation of hidden form fields.
The operational impact of this vulnerability extends beyond simple financial loss, as it compromises the trust relationship between merchants and customers within the payment ecosystem. Attackers can potentially increase the transaction amount by modifying the hidden AMOUNT field, leading to unauthorized financial gains. This vulnerability can result in significant monetary losses for merchants, customer dissatisfaction, and potential legal ramifications. The attack vector is particularly concerning as it operates through the standard payment flow, making detection difficult and potentially allowing for large-scale fraudulent transactions. The vulnerability's impact aligns with ATT&CK technique T1070.004 - Indicator Removal on Host, as the manipulation occurs without obvious signs of tampering, and T1566.001 - Phishing, as the attack often occurs through legitimate payment interfaces.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and sanitization mechanisms within the payment processing system. Organizations should enforce strict validation of all transaction parameters including the AMOUNT field, regardless of the state of other URL fields. The system should implement server-side validation that cannot be bypassed through client-side modifications, ensuring that all transaction values are verified against expected ranges and formats. Security measures should include cryptographic validation of transaction data, implementing proper session management, and ensuring that all payment parameters are validated at multiple points in the transaction process. Additionally, regular security audits and penetration testing should be conducted to identify similar validation weaknesses in payment processing systems. The remediation approach should follow security best practices outlined in OWASP Top Ten and PCI DSS requirements, specifically addressing validation and input sanitization controls to prevent unauthorized modification of payment transaction values.