Decrypting transport layer security traffic without man-in-the-middle proxy
A network security platform (NSP) device and interaction method are disclosed. The interaction method provides network packet analysis for secure transmission protocols using ephemeral keys or keys that are negotiated dynamically. The NSP may be part of an Intrusion Protection System, or firewall. The disclosed approach does not use man-in-the-middle proxy. Instead, it includes monitoring connections ends: client and/or server, to intercept the required data or negotiated (or changed) encryption keys. Decrypted data may be sent to an NSP sensor in a secure manner for analysis. Alternatively, intercepted keys used for the encrypt/decrypt operations may be sent to an NSP sensor in a secure manner every time they are changed. The NSP sensor may then use the obtained keys to decrypt traffic prior to providing it to the inspection engines. Embodiments focused on inbound traffic to a web server may coordinate between a web server and an NSP.
1. A method of analyzing encrypted network traffic on a sensor device located in a network communication path between a client device and a server device, the method comprising:
detecting, at the sensor device, a client initiated hello message sent from the client device to the server device;
copying first information from the client initiated hello message to, in part, track a session initiation handshake of a session, wherein the client initiated hello message is a first message of the handshake;
sending the client initiated hello message to the server device;
detecting, at the sensor device, a response to the client initiated hello in a server hello message sent from the server device to the client device;
copying second information from the server hello message to, in part, track the session initiation handshake, wherein the first and second information represent information used to uniquely identify at least one encryption key data stored in a memory of the sensor device for a plurality of sessions concurrently active on the sensor device;
detecting, at the sensor device, a negotiation of encryption key information for the session;
storing third information from the negotiation;
detecting, at the sensor device, encrypted data message information sent from the client device to the server device as part of the session; and
using the first, second, and third information to analyze the encrypted data message information.
2. The method of claim 1 , wherein the third information represents encryption keys negotiated for the session.
3. The method of claim 1 , wherein the session represents a Transport Layer Security (TLS) communication on a transmission control protocol (TCP) session.
4. The method of claim 1 , further comprising:
monitoring the session to identify a change in encryption keys and updating the at least one encryption key data stored in the memory of the sensor device.
5. The method of claim 4 , wherein monitoring the session comprises detecting, at the sensor device, a ChangeCipherSpec communication between the client device and the server device.
6. The method of claim 1 , wherein fourth information is sent from the server device to the sensor device via a secure secondary communication path in addition to data sent via the session.
7. The method of claim 6 , wherein the fourth information includes data from the session already decrypted at the server device.
8. The method of claim 6 , wherein the fourth information includes encryption key information regarding the session previously negotiated at the server device.
9. The method of claim 6 , wherein the secure secondary communication path uses an independent and secure additional network communication path between the server device and the sensor device.
10. The method of claim 9 , wherein the independent and secure additional network communication path comprises a virtual private network or a separate physical network.
11. A method of analyzing encrypted network traffic on a sensor device located in a network communication path between a client device and a server device, the method comprising:
detecting, at the sensor device, a client initiated hello message sent from the client device to the server device;
copying first information from the client initiated hello message to, in part, track a session initiation handshake of a session, wherein the client initiated hello message is a first message of the handshake;
sending the client initiated hello message to the server device;
detecting, at the sensor device, a response to the client initiated hello in a server hello message sent from the server device to the client device;
copying second information from the server hello message to, in part, track the session initiation handshake;
detecting, at the sensor device, a negotiation of encryption key information for the session;
storing third information from the negotiation;
detecting, at the sensor device, encrypted data message information sent from the client device to the server device as part of the session; and
using the first, second, and third information to analyze the encrypted data message information, wherein fourth information is sent from the server device to the sensor device via a secure secondary communication path in addition to data sent via the session, wherein the secure secondary communication path uses a non-network communication path between the server device and the sensor device.
12. A non-transitory computer readable medium comprising instructions stored thereon, that when executed by one or more processors cause the one or more processors to:
detect, at a sensor device, a client initiated hello message sent from a client device to a server device;
copy first information from the client initiated hello message to, in part, track a session initiation handshake of a session, wherein the client initiated hello message is a first message of the handshake;
send the client initiated hello message to the server device;
detect, at the sensor device, a response to the client initiated hello message in a server hello message sent from the server device to the client device;
copy second information from the server hello message to, in part, track the session initiation handshake;
detect, at the sensor device, a negotiation of encryption key information for the session;
store third information from the negotiation;
detect, at the sensor device, encrypted data message information sent from the client device to the server device as part of the session; and
use the first, second, and third information to analyze the encrypted data message information, wherein fourth information representing information used to uniquely identify at least one encryption key data stored in a memory of the sensor device for a plurality of session concurrently active on the sensor device is received from the server device at the sensor device via a secure secondary communication path in addition to data sent via the session.
13. The non-transitory computer readable medium of claim 12 , wherein the third information represents encryption keys negotiated for the session.
14. A sensor device comprising:
one or more processing units;
a memory communicatively coupled to the one or more processing units;
a network interface communicatively coupled to the memory and the one or more processing units; and
a secondary communication interface communicatively coupled to the memory and the one or more processing units, wherein the memory stores instructions that when executed by the one or more processing units cause the one or more processing units to:
detect, at the sensor device, a client initiated hello message from a client device to a server device, the client initiated hello message sent over a network accessible by the network interface;
copy first information from the client initiated hello message to, in part, track a session initiation handshake of a session, wherein the client initiated hello message is a first message of the handshake;
send the client initiated hello message, via the network interface, to the server device;
detect, at the sensor device, a response to the client initiated hello message in a server hello message sent from the server device to the client device;
copy second information from the server hello message to, in part, track the session initiation handshake;
detect, at the sensor device, a negotiation of encryption key information for the session;
store third information from the negotiation, wherein the first and second information represent information used to uniquely identify at least one encryption key data stored in a memory of the sensor device for a plurality of session concurrently active on the sensor device and the third information represents encryption keys negotiated for the session;
detect, at the sensor device, encrypted data message information sent from the client device to the server device as part of the session; and
use the first, second, and third information to analyze, using the one or more processing units, the encrypted data message information.
15. The sensor device of claim 14 , wherein the instructions further cause the one or more processing units to:
monitor the session to identify a change in encryption keys and update the at least one encryption key data stored in the memory of the sensor device.
16. The sensor device of claim 14 , wherein fourth information is sent from the server device to the sensor device via a secure secondary communication path in addition to data sent via the session.
17. The sensor device of claim 14 , wherein the third information represents encryption keys negotiated for the session and the third information is received at the sensor device from the server device via a secure secondary communication path using the secondary communication interface.