In response to feedback from operational security communities, CAIDA's source address validation measurement project (https://spoofer.caida.org) is automatically generating monthly reports of ASes originating prefixes in BGP for systems from which we received packets with a spoofed source address. We are publishing these reports to network and security operations lists in order to ensure this information reaches operational contacts in these ASes. This report summarises tests conducted within usa, can. Inferred improvements during Dec 2023: none inferred Source Address Validation issues inferred during Dec 2023: ASN Name First-Spoofed Last-Spoofed 3356 LEVEL3 2016-03-06 2023-12-21 209 CENTURYLINK-US-LEGACY-QWEST 2016-08-16 2023-12-29 20412 CLARITY-TELECOM 2016-09-30 2023-12-30 6181 FUSE-NET 2016-10-10 2023-12-13 25787 ROWE-NETWORKS 2016-10-21 2023-12-30 271 BCNET 2016-10-24 2023-12-10 701 UUNET 2017-06-14 2023-12-04 46997 2021-12-22 2023-12-29 12183 TALKIE-COMMUNICATIONS 2022-12-10 2023-12-26 3701 NERONET 2023-04-18 2023-12-28 400282 2023-04-27 2023-12-30 46690 SNET-FCC 2023-05-20 2023-12-26 20119 ARROW 2023-10-19 2023-12-04 26721 INYO 2023-12-17 2023-12-17 393577 SCCNET 2023-12-19 2023-12-28 Further information for these tests where we received spoofed packets is available at: https://spoofer.caida.org/recent_tests.php?country_include=usa,can&no_block=1 Please send any feedback or suggestions to spoofer-info@caida.org