Title: Payment bypass Product: WordPress NAB Transact WooCommerce Plugin Vendor Homepage: https://woocommerce.com/products/nab-transact-direct-post/ Vulnerable Version: 2.1.0 Fixed Version: 2.1.2 CVE Number: CVE-2020-11497 Author: Jack Misiura from The Missing Link Website: https://www.themissinglink.com.au Timeline: 2020-03-27 Disclosed to Vendor 2020-03-29 Vendor publishes first fix 2020-04-04 Vendor publishes second fix 2020-08-17 Fix confirmed 2020-08-20 Publication 1. Vulnerability Description The WordPress NAB Transact WooCommerce plugin does not validate the origin of payment processor status requests, allowing orders to be marked as fully paid by issuing a specially crafted GET request during the ordering workflow. 2. PoC When presented with a payment screen, instead of submitting payment information, issue the following GET request to the site: https://example-site.com/?wc-api=WC_Gateway_Nab_Direct_Post&order=XXXX&key= wc_order_YYYYY&is_crn=0&txnid=ZZZZZ&refid=WooCommerceXXXX&rescode=00&restext=Approved Where XXXX is the order number and YYYY is the order code which have been present before during the workflow. If these are not presented, submit invalid payment information and get a declined message. Now brute-force the order number which is sequential. Doing so will mark any existing pending orders as fully paid. 3. Solution The vendor provides an updated version (2.1.2) which should be installed immediately. 4. Advisory URL https://www.themissinglink.com.au/security-advisories Jack Misiura​ Application Security Consultant a 9‑11 Dickson Avenue Artarmon NSW 2064 p 1300 865 865 os +61 2 8436 8585 w <https://www.themissinglink.com.au/> themissinglink.com.au <https://www.linkedin.com/company/the-missing-link-pty-ltd/> <https://www.facebook.com/The-Missing-Link-268395013346228/?ref=bookmarks> <https://twitter.com/TML_au> <https://www.youtube.com/channel/UC2kd4mDmBs3SjW4lX3fFHnQ> <https://www.instagram.com/the_missing_link_it/> <https://www.themissinglink.com.au/robotic-process-automation> ​CAUTION - This message may contain privileged and confidential information intended only for the use of the addressee named above. If you are not the intended recipient of this message you are hereby notified that any use, dissemination, distribution or reproduction of this message is prohibited. If you have received this message in error please notify The Missing Link immediately. Any views expressed in this message are those of the individual sender and may not necessarily reflect the views of The Missing Link.