That depends on how you define "wide scale infrastructure sabotage". I believe that this is resulting from: https://blog.torproject.org/blog/tor-security-advisory-relay...

January 30 to July 4, 2014 someone set up 115 tor nodes on fdcservers.net (total cost maybe ~$200k?), which was 6.4% of entry guard capacity. Clients talk to 3 guard nodes for an average of 45 days each, which means they probably picked a guard ~12 times during this period. Each guard-picking attempt had a ~6.4% chance of landing one of these bad guards, or a 55% chance across all attempts.

"We know the attack looked for users who fetched hidden service descriptors... The attack probably also tried to learn who published hidden service descriptors, which would allow the attackers to learn the location of that hidden service."