Ok Kiklo - let's dance.
That an oldie.
https://www.youtube.com/watch?v=iNLXxDMxe18
..the rich guys that can spam the network until your timelocks expire, it is easy as pie.
Nah.. Let's say I want to cash out $100. All I need to do is pay a fee higher that the LOWEST the spammer pays.. Sooo.. If I'm prepared to pay $1, the spammer would have to spam the network, with fees OVER $1 for 100's / 1000's of TXNS to prevent mine from getting on.. no way is that worth it.
, Let's Say 100 other users Time Locks are expiring at the same time as yours , and all drawing out at least $100.
Total amount is now 100users*$100=$10,000
Average # of transactions per block ~2000.
At $1 each , it cost me $2,000 bucks to spam the block locking out all of your transactions and including mine, that lets me steal the entire $10,000 .
So My Profit is $8,000 , not bad for less than 30 minutes worth of work.
* The only poor people able to pull it off , are the Hackers that learn to Hack the LN Nodes, and modify the timelocks ahead of schedule.* 
Nope.. AT NO STAGE am I having to TRUST the LN node to sign anything on my behalf. All the clever crypto-shit is done by the client, on his machine, and he certainly isn't going to sign a txn that has 'funny' timelock schedules.. The worst the hackers can do is force me to cash out, if the LN node starts spewing rubbish.
Until segwit is activated, you have to trust them. (Even LN devs warn you of this.)
If segwit is ever activated,
And a Hacker Hacks an LN Node,
he could have it Lie to you about the route or fees or maybe even corrupting the preimage , triggering a roll back of the payment.
http://bitfury.com/content/5-white-papers-research/whitepaper_flare_an_approach_to_routing_in_lightning_network_7_7_2016.pdf
Quote
Requirement (Security).
As some of nodes may demonstrate Byzantine behaviour (e.g., by lying about fees or routes),
routing in LN should have protection mechanisms to prevent or mitigate harm
from such actions and guarantee that a sender would not lose his money even in a worst-case scenario.
Such mechanisms should include:
the ability to verify route existence
(seeAppendix A for the details on a possible implementation of the verification procedure)
the possibility to roll back the payment in case a node on the payment route provides the wrong
information on channel properties (this is already discussed in the LN white paper).
As some of nodes may demonstrate Byzantine behaviour (e.g., by lying about fees or routes),
routing in LN should have protection mechanisms to prevent or mitigate harm
from such actions and guarantee that a sender would not lose his money even in a worst-case scenario.
Such mechanisms should include:
the ability to verify route existence
(seeAppendix A for the details on a possible implementation of the verification procedure)
the possibility to roll back the payment in case a node on the payment route provides the wrong
information on channel properties (this is already discussed in the LN white paper).
Slickest thing for an Hacker to do is Trick the Neighborhood Discovery
to forward the preimage to himself so he can steal the funds directly.
By updating one LN, Network Discovery Paths, you update all of them.
http://bitfury.com/content/5-white-papers-research/whitepaper_flare_an_approach_to_routing_in_lightning_network_7_7_2016.pdf
Page 15 , goes on about Network Discovery
