what did they used?

11. (S) On May 29, Konstantin Koloskokov, Commissar of
the pro-Kremlin youth group Nashi in Transnistria,
claimed responsibility for some of the early cyber
attacks. While not discounting the possibility of his
involvement, XXXXXXXXXXXX noted that some of the
attacks were  extremely sophisticated; beyond the technical
abilities  of an amateur. To illustrate the point, XXXXXXXXXXXX
 and  XXXXXXXXXXXX described an attack that used a mysterious
data  packet to crash a GOE and Elion router so quickly that
the Estonians are still uncertain how it was done.

>used a mysterious data  packet

spooky data packet

Never mind that almost every one agrees that it was just a typical DDoS (whether it was a UDP flood or not, is not stated).  And lets forget that Estonia is far easier to take down than Amazon.