A group of 13 defendants who had been charged in an attack on PayPal's website pleaded guilty and admitted to the December 2010 attack over PayPal's suspension of Wikileaks accounts.
Following the release of a large amount of classified documents by Wikileaks, PayPal suspended its accounts so the anti-secrecy website could no longer receive donations.
In retribution, the group "Anonymous" coordinated and executed denial-of-service attacks against PayPal under "Operation Payback".
A 22-year-old university student from the UK, Christopher Weatherhead, has already been convicted for his role in the wide-ranging attacks.
The group of defendants who pleaded guilty were composed of 11 men and two women. Ten of them pleaded to a felony charge, but will be allowed to change that to a misdemeanor next year if they do not violate terms of their agreement before sentencing, according to the US attorney's statement.
The three other defendants agreed to misdemeanor charges.