System and method for managing tiered blacklists for mitigating network attacks

1. A computer-implemented method to manage blacklists used for mitigating threat traffic associated with a network attack, the method comprising:

manage, using a central blacklist manager, first, second and third mitigation systems, wherein the first mitigation system includes a first blacklist, the second mitigation system includes a second blacklist and the third mitigation system includes a third blacklist and wherein the first blacklist is upstream the second and third blacklists with the second blacklist being upstream to the third blacklist relative to one or more protected devices, and wherein the central blacklist manager has a processor such that upon execution of instructions is configured to:

monitor the first blacklist used by a first mitigation process of the first mitigation system and determine an amount of time a blacklist entry has been on the first blacklist;

monitor the second blacklist used by a second mitigation process of the second mitigation system and determine an amount of time a blacklist entry has been on the second blacklist;

monitor the third blacklist used by a third mitigation process of the third mitigation system and determine an amount of time a blacklist entry has been on the third blacklist, whereby a blacklist entry is moved from the third blacklist to the second blacklist if it is determined the blacklist entry was on the third blacklist beyond a threshold time, and move a blacklist entry from the second blacklist to the first blacklist if it is determined the blacklist entry was on the second blacklist beyond the threshold time;

determine an amount of time entries are included with the first blacklist;

determine if any of the time entries have been included with the first blacklist for more than a threshold amount of time; and

remove from the first blacklist each blacklist entry determined to have been included with the first blacklist for more than the threshold amount of time.

2. The method of claim 1 , wherein monitoring the first and second blacklists includes obtaining statistics related to mitigation of threat traffic associated with a network attack using the second blacklist, and does not include obtaining statistics related to mitigation of threat traffic associated with a network attack using the first blacklist.

3. The method of claim 2 , wherein the statistics include at least one of an indication of an amount of traffic sent by sources associated with entries included in the second blacklist or a length of time the respective entries have been included on the second blacklist.

4. The method of claim 1 , wherein the first and second mitigation processes are performed by the respective first and second mitigation devices, and the first and second mitigation devices have two different types, the types being selected from a threat management system (TMS) performing software threat management with software mitigation using software blacklisting; a switch device integrated with a chassis of the TMS, the switch device performing hardware mitigation using hardware blacklisting; and an offloaded hardware device physically remote from the chassis, the offloaded hardware device performing hardware mitigation using hardware blacklisting.

5. The method of claim 1 , wherein the first blacklist has limited space for including entries available relative to the second blacklist.

6. The method of claim 5 further comprising:

monitoring incoming network traffic;

comparing a characteristic of sources sending network traffic determined to include threat traffic to entries that were previously stored on the first blacklist;

identifying, based on the comparison, sources that are associated with entries previously stored on the first blacklist; and

adding entries previously stored on the first blacklist that are associated with the identified sources.

7. The method of claim 6 , further comprising:

determining whether a source of the network traffic determined to be transmitting threat traffic is transmitting a larger amount of threat traffic than has been transmitted by sources associated with entries in the second blacklist;

adding an entry associated with the source to the third blacklist if it is determined that the source is transmitting the larger amount of threat traffic; and

adding an entry associated with the source to the second blacklist if it is determined that the source is not transmitting the larger amount of threat traffic.

8. The method of claim 1 , wherein the first mitigation process is performed upstream relative to the central blacklist manager.

9. The method of claim 1 , wherein moving entries to and from the second blacklist is more time consuming than moving entries to the first blacklist.

10. The method of claim 1 , wherein each of the first, second and third mitigation systems includes a computer processor independent of one another for monitoring the respective blacklist of each of the first, second and third mitigation systems.