Network surveillance

• US 6,321,338 B1
• Filed: 11/09/1998
• Issued: 11/20/2001
• Est. Priority Date: 11/09/1998
• Status: Expired due to Term

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Porras, Phillip A., Valdes, Alfonso
• Primary Examiner(s): Heckler, Thomas M.
• Application Number:
  US09/188,739
• Time in Patent Office: 1,107 Days
• Field of Search: 713/201, 709/224
• US Class Current: 726/25
• CPC Class Codes: H04L 41/142 using statistical or mathematical methods
• CPC Class Codes: H04L 43/00 Arrangements for monitoring or testing data switching networks
• CPC Class Codes: H04L 43/06 Generation of reports
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 43/0888 Throughput
• CPC Class Codes: H04L 43/12 Network monitoring probes
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04L 63/1408 by monitoring network traffic monitoring network traffic per se H04L43/00
• CPC Class Codes: H04L 63/1416 Event detection, e.g. attack signature detection
• CPC Class Codes: H04L 63/145 the attack involving the propagation of malware through the network, e.g. viruses, trojans or worms
• CPC Class Codes: H04L 63/1458 Denial of Service

Abstract

A method of network surveillance includes receiving network packets handled by a network entity and building at least one long-term and a least one short-term statistical profile from a measure of the network packets that monitors data transfers, errors, or network connections. A comparison of the statistical profiles is used to determine whether the difference between the statistical profiles indicates suspicious network activity.

Claims

1. A method of network surveillance, comprising:

receiving network packets handled by a network entity;

building at least one long-term and at least one short-term statistical profile from at least one measure of the network packets, the at least one measure monitoring data transfers, errors, or network connections;

comparing at least one long-term and at least one short-term statistical profile; and

determining whether the difference between the short-term statistical profile and the long-term statistical profile indicates suspicious network activity.

2. The method of claim 1, wherein the measure monitors data transfers by monitoring network packet data transfer commands.

3. The method of claim 1, wherein the measure monitors data transfers by monitoring network packet data transfer errors.

4. The method of claim 1, wherein the measure monitors data transfers by monitoring network packet data transfer volume.

5. The method of claim 1, wherein the measure monitors network connections by monitoring network connection requests.

6. The method of claim 1, wherein the measure monitors network connections by monitoring network connection denials.

7. The method of claim 1, wherein the measure monitors network connections by monitoring a correlation of network connections requests and network connection denials.

8. The method of claim 1, wherein the measure monitors errors by monitoring error codes included in a network packet.

9. The method of claim 8, wherein an error code comprises a privilege error code.

10. The method of claim 8, wherein an error code comprises an error code indicating a reason a packet was rejected.

11. The method of claim 1, further comprising responding based on the determining whether the difference between the short-term statistical profile and the long-term statistical profile indicates suspicious network activity.

12. The method of claim 11, wherein responding comprises transmitting an event record to a network monitor.

13. The method of claim 12, wherein transmitting the event record to a network monitor comprises transmitting the event record to a hierarchically higher network monitor.

14. The method of claim 13, wherein transmitting the event record to a network monitor comprises transmitting the event record to a network monitor that receives event records from multiple network monitors.

15. The method of claim 14, wherein the monitor that receives event records from multiple network monitors comprises a network monitor that correlates activity in the multiple network monitors based on the received event records.

16. The method of claim 11, wherein responding comprises altering analysis of the network packets.

17. The method of claim 11, wherein responding comprises severing a communication channel.

18. The method of claim 1, wherein the network packets comprise TCP/IP packets.

19. The method of claim 1, wherein the network entity comprises a gateway, a router, or a proxy server.

20. The method of claim 1, wherein the network entity comprises a virtual private network entity.

21. A method of network surveillance, comprising:

monitoring network packets handled by a network entity;

building a long-term and multiple short-term statistical profiles of the network packets;

comparing one of the multiple short-term statistical profiles with the long-term statistical profile; and

determining whether the difference between the one of the multiple short-term statistical profiles and the long-term statistical profile indicates suspicious network activity.

22. The method of claim 21, wherein the multiple short-term statistical profiles comprise profiles that monitor different anonymous FTP sessions.

23. The method of claim 21, wherein building multiple short-term statistical profiles comprises deinterleaving packets to identify a short-term statistical profile.

24. A computer program product, disposed on a computer readable medium, the product including instructions for causing a processor to:

receive network packets handled by a network entity;

build at least one long-term and at least one short-term statistical profile from at least one measure of the network packets, the measure monitoring data transfers, errors, or network connections;

compare at least one short-term and at least one long-term statistical profile; and

determine whether the difference between the short-term statistical profile and the long-term statistical profile indicates suspicious network activity.

25. A method of network surveillance, comprising:

receiving packets at a virtual private network entity; and

building at least one long-term and at least one short-term statistical profile based on the received packets, and

comparing at least one long-term statistical profile with at least one short-term statistical profile to determine whether the packets indicate suspicious network activity.

26. The method of claim 25, further comprising decrypting the packets before statistically analyzing the packets.

27. The method of claim 25, further comprising not decrypting the packets before statistically analyzing the packets.