Watch the Powerpoint Presentation by the Team at LANL.
defeating a seal: opening a seal, then resealing (using the original seal or a counterfeit) without being detected. Defeating seals is mostly about fooling people, not beating hardware (unlike defeating locks, safes, or vaults)!
attacking a seal: undertaking a sequence of actions designed to defeat it.
This presentation is by the Vulnerability Assessment Team at LANL (Los Alamos National Labboratory).