Method, device and program for detecting a vulnerability in a communication network

Abstract

The invention relates to a method for detecting a vulnerability in a communication network, comprising the steps of determining (200), from a corpus of documents, at least one signature characteristic of a communication standard associated with at least one specific cryptographic function; applying (201) a detection rule to at least one data packet captured on the network, said rule being configured to activate upon detection of said at least one determined characteristic signature; and upon activation of said rule, transmitting (202) an alert comprising at least one identifier of an originating and / or receiving device of said network flow. A device adapted for implementing such a method is also proposed. Figure 2.

Description

Title of the invention: Method, device and program for detecting a vulnerability in a communication network Technical field

[0001] The invention belongs to the field of telecommunications and relates in particular to a method for detecting a vulnerability in a communication network, more precisely a vulnerability to attacks carried out from a quantum computer. Prior art

[0002] The progress made in the field of quantum computing is now posing a concrete challenge to the security devices of communication networks. Indeed, while quantum algorithms, such as Shor's, Grover's and Simon's algorithms, have until now made it possible to conceptually resolve certain computational problems on which widely deployed security mechanisms are based, the emergence of computers adapted to implement these algorithms makes this threat very concrete.

[0003] Indeed, while the best classical algorithms for solving these problems have exponential complexity in general, quantum algorithms can produce an answer in polynomial time.

[0004] Although a sufficiently large and reliable quantum computer is not yet available to potential hackers, encrypted streams captured today by an attacker could be decrypted by quantum algorithms later and reveal secrets that could still have value in the future. It is therefore imperative to implement so-called post-quantum security mechanisms today, which maintain a high level of security against a quantum computer.

[0005] Cryptographic techniques vulnerable to attacks based on quantum computers are widely deployed in networks and infrastructures in service today. It is therefore imperative to identify and update services that are likely to be affected today.

[0006] However, the extent of certain communication networks and the diversity of the services they support do not allow for a simple list of services likely to be affected to be established. This difficulty in establishing an exhaustive map of vulnerable services deployed in a network is all the more exacerbated when users are offered the possibility of installing applications themselves on their workstations and when these applications are subject to frequent updates. Thus, the security mechanisms used to protect services are likely to vary over time.

[0007] Thus, exhaustively identifying services vulnerable to quantum attacks is a difficult and time-consuming task.

[0008] There is therefore a need for a technique enabling communications network operators to reliably and exhaustively detect and identify services likely to be vulnerable to attacks carried out using quantum computers. Summary of the invention

[0009] To this end, a method for detecting a vulnerability in a communication network is proposed, comprising the following steps: - Determination, from a corpus of documents, of at least one signature characteristic of a communication standard associated with at least one particular cryptographic function, - Application of a filtering rule to at least one data packet captured on a communication network, said rule being configured to activate upon detection of said at least one determined characteristic signature, - Upon activation of said rule, transmission of an alert comprising at least one identifier of a device at the origin and / or a device receiving said data packet.

[0010] The general principle of the invention is thus based on the identification of documents comprising a reference to a particular cryptographic technology deemed vulnerable, and the determination in this document of a particular technical characteristic from which it is possible to detect the implementation of said cryptographic technique by capturing packets transiting over a network to raise alerts and / or take mitigation measures when an implementation is detected.

[0011] In this way, it is possible to continuously carry out an inventory of the services deployed on a communication network that use cryptographic functions that are considered vulnerable. Detection rules are generated from structured or unstructured documents, for example technical documents such as standards (IETF RFCs (Request For Comments), documents published by the ITU or 3GPP), or computer source code files, XML or HTML documents, technical software documentation, configuration files, etc. The rules are applied to data packets captured on a computer network to detect use so that when a rule is activated, an alert is raised to identify the service(s) concerned.The detection process thus enables continuous monitoring of networks, allowing rapid detection of new vulnerabilities, for example, after a new crypto function. topographical is implemented following an update of software or its configuration.

[0012] According to a particular embodiment, the particular cryptographic function is a function based on a discrete logarithm problem or the problem of integer factorization, a symmetric cryptographic function or a cryptographic hash function.

[0013] Cryptographic constructions whose security relies on the discrete logarithm problem (notably Diffie-Hellman key exchange and ECDSA signature), or on the integer factorization problem (notably RSA encryption and signature) become vulnerable to an attacker with a properly sized quantum computer. More generally, public key algorithms relying on integer factorization are vulnerable to an attack using a quantum computer (e.g., algorithms such as RSA, Paillier, Naccache-Stem, Rabin, Benaloh, Blum-Goldwasser, Damgârd-Jurik, Goldwasser-Micali, Okamoto-Uchiyama, Schmidt-Samoa). In addition, symmetric cryptographic functions such as AES (Advanced Encryption Standard), as well as cryptographic hash functions such as SHA (Secure Hash Algorithm), are generally also vulnerable. Their detection thus makes it possible to increase network security.

[0014] According to a particular embodiment, the method is such that the step of determining at least one characteristic signature associated with at least one particular cryptographic function comprises the following sub-steps: - Analysis of the document corpus to detect at least one reference to at least one particular cryptographic function, - When at least one reference is detected, determination of a signature characteristic of a communication standard from the document in which the reference is detected.

[0015] When a reference to a cryptographic system likely to be vulnerable to an attack is detected in a document of the corpus associated with a communication standard, a characteristic of the standard in question is determined from this document, the characteristic being adapted to detect the implementation of this standard in a communication.

[0016] The analysis of the documents in the corpus makes it possible to identify one or more characteristic elements of a communication protocol implementing a particular cryptographic system.

[0017] In a particular embodiment, the analysis step comprises applying to the corpus of documents a classification model previously trained from documents in which the particular cryptographic function is identified at prior.

[0018] In a particular embodiment, a characteristic signature of a communication standard comprises at least one of the following elements: - A communication port number, - An identifier of a communication standard, - A protocol header field, - A parameter size, - An arrangement according to a particular order of parameters.

[0019] It is thus proposed to automate the identification and extraction of a destination UDP or TCP port number of a message conforming to a communication standard described in at least one document of the corpus, a standard identifier and / or a particular value in a header intended to be inserted into a message. Such information is characteristic of a communication standard and makes it possible to generate a detection rule configured to be activated when a particular message is captured on a communication network.

[0020] According to a particular embodiment, the method is such that the alert further comprises an identifier of a service at the origin and / or of a recipient equipment of said data packet.

[0021] The activation of a rule is characteristic of the detection of a communication associated with a cryptographic function identified as vulnerable. It is proposed to issue an alert in which one or more devices or services associated with this communication are identified. In this way, it is possible to draw up an exhaustive inventory of the services and / or devices that require a security update.

[0022] According to another aspect, a device for detecting a vulnerability in a communication network is proposed, the device comprising a processor coupled to a memory in which instructions configured to implement the following steps are recorded, when they are executed by the processor: - Determination, from a corpus of documents, of at least one signature characteristic of a communication standard associated with at least one particular cryptographic function, - Application of a detection rule to at least one data packet captured on a communication network, said rule being configured to activate upon detection of said at least one determined characteristic signature, and - Upon activation of said rule, transmission of an alert comprising at least one identifier of a device at the origin and / or a device receiving said network flow.

[0023] The invention also relates to a server comprising a detection device such as as described above.

[0024] In a particular embodiment, the different steps of the detection method are determined by computer program instructions.

[0025] Consequently, the invention also relates to a computer program comprising instructions adapted to the implementation of the steps of a detection method as described above, when the program is executed by a processor.

[0026] This program may use any programming language, and be in the form of source code, object code, or code intermediate between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0027] The invention also relates to a recording medium readable by a computer on which is recorded a computer program comprising instructions for executing the steps of a detection method as described above.

[0028] The information medium may be any entity or device capable of storing the program. For example, the medium may comprise a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, a flash memory, or a magnetic recording means, such as a hard disk.

[0029] On the other hand, the information medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention may in particular be downloaded from an Internet-type network.

[0030] Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the methods in question.

[0031] The various embodiments or features mentioned above can be added independently or in combination with each other, to the steps of the detection method.

[0032] The devices, servers and programs have advantages similar to those of the method to which they correspond. Brief description of the figures

[0033] Other characteristics and advantages will appear on reading a preferred embodiment described with reference to the appended drawings among which:

[0034] [Fig.l] [Fig.l] represents an example of a communication network,

[0035] [Fig.2] [Fig.2] is a flowchart illustrating the main steps of a detection method according to a particular embodiment, and

[0036] [Fig.3] [Fig.3] is a block diagram illustrating the architecture of a device suitable for implementing a detection method according to a particular embodiment. Detailed description

[0037] [Fig. 1] represents in a simplified manner a communication network RI comprising equipment E1 to E4. The network RI is for example a local area network (LAN) comprising servers and / or user workstations E1 to E4. Of course, the invention which will be described can be applied to any type of network and the example of [Fig. 1] is given only for illustrative purposes. For example, the network RI can comprise other equipment not shown, such as routers or gateways. The network RI can be a physical network or a virtual network without limiting the invention.

[0038] The network RI also comprises a probe S adapted to monitor and / or capture the traffic circulating on the network, and in particular the messages sent and / or received by the different devices. Although this is not shown in [Fig.l] to simplify the description which follows, the network RI may comprise a plurality of probes S in order to monitor different branches of the network.

[0039] Thus, when a message is for example sent by the equipment E1 to the equipment E4, the probe S can detect and capture a data packet in which the message is transmitted and obtain a copy thereof. The probe S can be adapted to thus capture data flows at different levels, for example on the physical layer, the data link layer, the transport layer or even at the application level.

[0040] The probe S is for example a computing device such as a server comprising a processor, a memory and a network interface (for example an Ethernet or WiFi® interface). The memory of the device comprises program instructions configured to control the network interface in order to capture and decode the data packets.

[0041] The probe S is adapted to implement a detection method according to a particular embodiment.

[0042] [Fig.2] is a flowchart illustrating the main steps of a method of detection according to a particular implementation.

[0043] The method comprises a first step 200 during which a corpus of documents is analyzed in order to extract at least one signature characteristic of a communication standard associated with at least one particular cryptographic function.

[0044] The corpus can consist of structured or unstructured documents. For example, it includes a set of standard documents, such as RFCs, documents offered by 3GPP, technical notices, source code, configuration files, etc.

[0045] In a particular embodiment, the analysis of the document corpus is carried out by an information extraction module configured to detect keywords characteristic of at least one particular cryptographic function. For example, the extraction module may comprise a lexical analyzer configured to detect the keyword “RSA” in a document corpus comprising RFCs published by the IETF. When the keyword is detected in at least one document, for example in the document “RFC4253”, the information extraction module is configured to determine an element characteristic of a communication standard from the content of the document, for example a port number or a format indicator. In this case, such an analyzer can extract an indication according to which port 22 is involved in the communication standard defined by RFC4253.

[0046] A format indicator is a sequence of characters or a numeric constant that identifies a particular file format or protocol. Such an indicator is known as a "magic number" or "magic cookie". For example, the DHCP protocol uses a format indicator consisting of the sequence "63 82 53 63" at the beginning of the option section of all packets; SSL / TLS transactions always begin with the message "client hello".

[0047] When such an association between a cryptographic function and a characteristic element of a communication protocol (such as a port number or a format indicator) is established from a document or a combination of documents, the association is stored in a database.

[0048] Of course, any suitable extraction technique can be considered to identify characteristics of communications protocols implementing particular cryptographic functions from a corpus of unstructured or semi-structured documents. For example, the analysis and extraction can be carried out by applying a supervised learning model previously trained for this purpose. Such a model is for example a recurrent neural network (RNN) or a self-attentive model such as a transformer. Such learning models are particularly suited to such an analysis task because they are designed to handle sequential data, in particular natural language. The learning model is previously trained from snippets of text or documents labeled as containing references to the cryptographic functions and / or characteristic signatures in question.

[0049] In a particular embodiment, the information extraction module is configured to detect in the documents of the corpus references to the algorithms AES (Advanced Encryption Standard), SHA (Secure Hash Algorithm), SHA-3, RSA (Rivest-Shamir-Adelman), ECDSA (Elliptic curve digital signature algorithm) and ECDH or DSA (Digital signature algorithm), or any other algorithm whose use we wish to detect.

[0050] The method comprises a step 201 during which at least one detection rule is applied to data packets captured on the network, said rule being configured to activate upon detection of said at least one determined characteristic signature.

[0051] For this, packets circulating on the network are captured by a conventional capture device comprising a network interface configured to intercept or copy data packets and an analysis module configured to apply filtering rules to the captured traffic so as to select the packets corresponding to one or more particular criteria, and in particular to select the packets comprising one or more characteristic elements of a communication protocol determined in step 200. Thus, for example, the detection rule is configured to inspect the IP packets and select the packets whose destination port signaled in the IP header corresponds to an IP port identified in a document of the corpus in which a reference to a particular cryptographic function is detected.In another example, the detection rule inspects the captured packets to identify a particular format indicator determined in step 200, and selects the packet when a particular format indicator is detected.

[0052] According to a particular embodiment, step 201 comprises the application of a learning model previously trained by supervised learning to detect the presence of a characteristic signature in the captured messages. For this, a learning model such as an artificial neural network (for example a CNN for Convolutional Neural Network) previously trained from labeled examples can be implemented to detect patterns in the data packets, particular headers, one or more port numbers, etc.).

[0053] The method finally comprises a step 202 of transmitting an alert when at least one packet flow causes the activation of a rule applied in step 201. The alert can be transmitted in a message and / or recorded in a database. Such an alert comprises at least one identifier of a source device and / or a recipient device of the message having triggered the activation of the filtering rule, for example an IP address, a UDP or TCP port, a machine name, etc. The alert can further comprise data making it possible to identify a protocol and / or a standard, or an application involved in the transmission of the message or the message flow having triggered the activation of the rule.

[0054] In a particular embodiment, the triggering of the alert causes a reconfiguration of a filtering device, for example upon detection of a flow of data associated with a cryptographic function deemed vulnerable, the alert can cause the isolation of the machine at the origin of the data flow by configuring firewall rules or a routing table.

[0055] [Fig.3] represents a simplified architecture of a device 300 adapted to implement the detection method according to a particular embodiment.

[0056] The device 300 comprises a data processing module comprising a storage space 301, for example a memory (MEM), a processing unit 302, equipped for example with a microprocessor (PROC), and controlled by a computer program (PGR) 303 whose instructions are configured to implement the detection method as described previously in relation to [Fig.2].

[0057] At initialization, the code instructions of the computer program 303 are for example loaded into the memory 301 before being executed by the processor of the processing unit 302. The microprocessor of the processing unit 302 implements, according to the instructions of the computer program 303, the steps of the detection method described above with reference to [Fig.2]

[0058] For this, the device 300 comprises communication means 304, for example an Ethernet or WiFi® network interface configured in promiscuous mode to capture all traffic circulating on the part of the network to which the network interface is connected, and not only the packets addressed to it. In other words, the network interface is configured not to filter packets on the MAC address and to accept all packets.

[0059] The device 300 also comprises an analysis module 305 adapted to apply a detection rule to at least one data packet captured on the network, said rule being configured to activate upon detection of at least one signature characteristic of a communication standard associated with at least one particular cryptographic function, said signature being determined by analysis of a corpus of documents or carrying out execution tests. In a particular embodiment, the module 305 is implemented by computer program instructions configured to examine at least one packet captured by the communication means 304, and compare at least one element of the message, for example a header, a port number or a format identifier, with at least said characteristic signature, and to activate said rule in the event of correspondence of the signature with an element of the message.

[0060] The device 300 also comprises an alert module 306, configured to transmit an alert when a detection rule is activated for at least one message captured by the communication means. The alert module is for example implemented by program instructions configured to identify a device and / or a service sending and / or receiving the message having activated the rule, and to record at least one characteristic of the alert in a database. In a particular embodiment, the alert module is configured by the program instructions to transmit an alert message to a particular device.

[0061] In a particular embodiment, the device 300 is included in a network node, for example in a probe, a gateway or a server.

Claims

Claims

1. Method for detecting a vulnerability in a communication network characterized in that it comprises the following steps: - Determination (200), from a corpus of documents, of at least one signature characteristic of a communication standard associated with at least one particular cryptographic function, - Application (201) of a detection rule to at least one data packet captured on the network, said rule being configured to activate upon detection of said at least one determined characteristic signature, - Upon activation of said rule, transmission (202) of an alert comprising at least one identifier of an equipment at the origin and / or of an equipment receiving said data packet.

2. The method of claim 1 wherein the particular cryptographic function is a function based on a discrete logarithm problem or the integer factorization problem, a symmetric cryptographic function, or a hash cryptographic function.

3. Method according to any one of the preceding claims in which the step of determining at least one characteristic signature associated with at least one particular cryptographic function comprises the following steps: - Analysis of the corpus of documents to detect at least one reference to at least one particular cryptographic function, - When at least one reference is detected, determination of a characteristic signature of a communication standard from the document in which the reference is detected.

4. The method of claim 3 wherein the analyzing step comprises applying to the corpus of documents a classification model previously trained from documents in which the function particular cryptographic technique is identified beforehand.

5. Method according to any one of the preceding claims in which the at least one signature characteristic of a communication standard comprises at least one of the following elements: - A communication port number, - An identifier of a communication standard, - A protocol header, - A parameter size, - An arrangement according to a particular order of parameters.

6. Method according to any one of the preceding claims in which the alert further comprises an identifier of a service at the origin and / or of a recipient equipment of said network flow.

7. Device for detecting a vulnerability in a communication network, the device comprising a processor (302) coupled to a memory (301) in which are recorded instructions (303) configured to implement the following steps, when executed by the processor: - Determination, from a corpus of documents, of at least one signature characteristic of a communication standard associated with at least one particular cryptographic function, - Application of a detection rule to at least one packet captured on a communication network, said rule being configured to be activated upon detection of said at least one determined characteristic signature, and - Upon activation of said rule, transmission of an alert comprising at least one identifier of an equipment at the origin and / or of an equipment receiving said data packet.

8.

9. Server comprising a device according to claim 7. Computer program comprising instructions configured to implement a detection method according to any one of claims 1 to 6, when said instructions are executed by a processor.

10. Information medium on which instructions are recorded configured to implement a detection method according to any one of claims 1 to 6

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