Pierluigi Paganini
February 14, 2021
PayPal has fixed a reflected cross-site scripting (XSS) vulnerability that was discovered in the currency converter feature of user wallets on February 19, 2020, close one year ago.
The ‘reflected XSS and CSP bypass’ vulnerability was reported by the bug bounty hunter “Cr33pb0y” through the HackerOne platform.
“An endpoint used for currency conversion was found to suffer from a reflected XSS vulnerability, where user input was not being properly sanitized in a parameter in the URL. This could lead to a malicious user injecting malicious JavaScript, HTML, or any other type of code that the browser may execute. The malicious script will execute in the browser page DOM of another user typically without their knowledge or consent.” reads the summary published by PayPal.
PayPal has implemented additional validation checks and sanitizer controls for user input in the currency exchange feature before being returned in the response.
According to PayPal, the flaw resided in the currency conversion endpoint and was caused by a failure to properly sanitize the input in a parameter in the URL.
An attacker could have exploited the flaw to inject malicious code (JavaScript, HTML, or any other language) that will be executed within the browser.
This means that the malicious script will execute in the browser page Document Object Model (DOM) of another user typically without their knowledge or consent.
In a real attack scenario, threat actors could trigger the flaw by tricking the victims into clicking on a specially crafted link.
Malicious payloads could be executed to carry out multiple malicious activities, such as stealing cookies and session tokens.
Cr33pb0y received a $2,900 reward as part of the bug bounty program.
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(SecurityAffairs – hacking, PayPal)
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