Excessive BGP AS-PATH prepending is a self-inflicted vulnerability
(World News Science)

In the Border Gateway Protocol (BGP), prepending is a technique used to deprioritize a route by artificially increasing the length of the AS-PATH attribute by repeating an autonomous system number (ASN). Route selection in BGP prefers the shorter AS path length, assuming all other criteria are equal. Therefore, a prepended route should be selected less often. To employ this technique correctly, a network operator would normally deprioritize a route by prepending their ASN in the AS-PATH attribute in their announcements to a subset of multiple transit providers. Unfortunately, as I will report below, prepending is frequently employed in an excessive manner such that it renders routes...