Security for Lightning Network nodes?
So I think you're missing some things. Since the Lightning node has bitcoins in the channel and can be used as a conduit for B to send or receive money, node A must have an automated way to sign bitcoin transactions and participate in lightning transactions. An attacker could theoretically use this ability to send bitcoins from the channel through the lightning network to themselves, in the case that the attacker compromises the machine in such a way as to have the ability to instruct the Lightning node to do those things. The private keys would still be in memory at very least, and so could potentially be accessible to kernel viruses.