US 11,695,796 B1 · Device vulnerability detection during device handshake

Abstract

Described are implementations that analyze the unencrypted messages of a cryptographic protocol handshake between two devices and/or the receipt or absence of encrypted messages of the handshake to detect security vulnerabilities of one or both of those devices. For example, the unencrypted messages of a TLS handshake between a client device and a server may be analyzed to determine security vulnerabilities of the client device. Because the disclosed implementations utilize the unencrypted messages of a handshake and/or detection of the receipt or absence of encrypted messages of the handshake, involvement in the handshake or decryption of encrypted messages of the handshake is not necessary. The requirement is that the disclosed implementations are able to observe the messages of a handshake that are used to establish a secure communication between the devices.

Claims22

Dependent claims

A computer-implemented method to determine one or more device vulnerabilities of a client device, comprising:

receiving, at a vulnerability detector, a client hello message sent from the client device to a server, the vulnerability detector positioned to observe messages sent between the client device and the server as part of a Transport Layer Security (“TLS”) handshake;
determining that a server certificate sent from the server to the client device in response to the client hello message is at least one of incorrectly signed or expired;
receiving, at the vulnerability detector, a client key exchange message sent from the client device to the server;
determining, with the vulnerability detector and based on receipt of the client key exchange message and determination that the server certificate is at least one of incorrectly signed or expired, that the client device validated the server based on an invalid server certificate;
generating, based at least in part on the processing of the client hello message and in response to determining that the client key exchange message was received and that the server certificate is at least one of incorrectly signed or expired, a client device vulnerability log indicating that the client device validated the server based on the invalid server certificate;
and
providing the client device vulnerability log to cause a vulnerability of the client device to be resolved.

4 more elements

A computing system, comprising:

one or more processors;
and
a memory storing program instructions that, when executed by the one or more processors, cause the one or more processors to at least:
receive a client hello message sent from a client device to a server as part of an encryption protocol handshake;
determine that at least one of a common name (“CN”) or a subject alternative name (“SAN”) included in a server hello message sent from the server to the client device in response to the client hello message does not match a server name indication (“SNI”) included in the client hello message;
detect a client key exchange message sent from the client device to the server;
determine, based at least in part on the detection of the client key exchange message and the determination that at least one of the CN or the SAN does not match the SNI, that the client device validated the server based on an invalid server certificate;
generate, based at least in part on the determination that at least one of the CN or the SAN does not match the SNI, a client device vulnerability log indicting that the client device validated the server based on the invalid server certificate;
and
provide the client device vulnerability log to cause a vulnerability of the client device to be resolved.

7 more elements

A method to determine a device vulnerability based on messages exchanged between a first device and a second device as part of a cryptographic protocol handshake to establish an encrypted communication between the first device and the second device, comprising:

receiving, as part of the cryptographic protocol handshake, a first message sent from the first device to the second device, wherein the first message is unencrypted and indicates at least one of a protocol version supported by the first device, a device time, a client random, or an indication of a plurality of algorithm suites supported by the first device;
receiving, as part of the cryptographic protocol handshake, a second message sent from the second device to the first device in response to the first message, wherein the second message is unencrypted and indicates at least one of a first algorithm suite from the plurality of algorithm suites selected by the second device, a certificate that includes a public key, or a server random;
receiving, as part of the cryptographic protocol handshake, a third message sent from the first device to the second device;
determining that at least one item included in the second message is inaccurate;
determining, based at least in part on receiving the third message and the determination that at least one item in the second message is inaccurate, that the first device improperly validated the second device;
generating a device vulnerability log that indicates that the first device improperly validated the second device;
and
providing the device vulnerability log to cause the device vulnerability of the first device to be resolved.

5 more elements

Dependencies are inferred from the claim text.

Device vulnerability detection during device handshake

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Device vulnerability detection during device handshake

Life of this patent

Abstract

Claims22