WO2016045541A1

WO2016045541A1 - Method and device for identifying the presence of man-in-the-middle

Info

Publication number: WO2016045541A1
Application number: PCT/CN2015/089949
Authority: WO
Inventors: 陈海兵
Original assignee: 阿里巴巴集团控股有限公司; 陈海兵
Priority date: 2014-09-26
Filing date: 2015-09-18
Publication date: 2016-03-31
Also published as: CN105516066B; CN105516066A; HK1222060A1

Abstract

A method for identifying the presence of a man-in-the-middle is disclosed, the method is used to solve the problem that a web client can not identify whether there is a man-in-the-middle between the web client and a server, thus the transmitted information may be subject to potential security threats. The method includes: obtaining the related information of the first certificate of the server received by the web client during the handshake process between the web client and the server, and the related information of the second certificate of the server received by the web client during the non handshake process between the web client and the server (21); determining whether the related information of the first certificate and the related information of the second certificate are matched (22). A device for identifying the presence of a man-in-the-middle is also disclosed.

Description

Method and device for identifying the presence of a middleman

Technical field

The present application relates to the field of computer technology, and in particular, to a method and apparatus for identifying the presence of an intermediary.

Background technique

In many cases, Internet users need to use a non-private terminal to access the Internet, such as using a computer provided by a company or Internet cafe. For the owner of such a terminal, the security requirements are not exactly the same as the actual user's security requirements of the terminal, and sometimes conflicts may occur. For example, for the actual user, it is hoped that during the online process, personal privacy such as bank account passwords will not be snooped; but for enterprises, in order to prevent their internal secrets from being maliciously leaked or to improve the efficiency of employees, it is hoped The actual user's Internet traffic is scanned or audited to determine the specific information transmitted by the actual user using the terminal.

Generally, for non-encrypted traffic, simple stream-based scanning can achieve the purpose of monitoring information; for Secure Sockets Layer, such as Hyper Text Transfer Protocol over Secure Socket Layer (HTTPS) (Secure Sockets Layer) , SSL) protocol to encrypt the encrypted traffic, you need to use proxy technology to achieve information monitoring. A schematic diagram of a typical proxy technology implementation is shown in Figure 1.

In Figure 1, the left box represents the client (Web Client) installed in the enterprise's terminal, and the middle box represents the SSL proxy (SSL Proxy1, deployed in the gateway or firewall device at the enterprise network exit), as shown in Figure 1. In the scenario, it is generally referred to as "middleman", and the box on the right represents the web server accessed by the client. Specifically, the name of the server may be "Alipay Web Server" as shown in FIG.

In Figure 1, the function of monitoring the specific information transmitted by the terminal is an SSL proxy. The implementation principle of the function is roughly as follows: the SSL proxy hijacks the SSL handshake request from the client, and then utilizes the The SSL handshake request initiates an SSL connection with the real server; after the SSL handshake with the server is successful, the SSL handshake with the client is resumed, and when the client performs an SSL handshake, a forged certificate is pushed to the client, so that The client trusts the SSL proxy, which in turn can obtain the information sent by the client.

It should be noted that, according to the design of the SSL protocol, it has the consistency check capability, that is, when it is attacked by a man-in-the-middle, the client will pop up an alarm to inform the user that the currently received certificate is illegal. However, for the company, the alarm is actually caused by the SSL agent deployed by itself. It is not the actual attack on the company network. Therefore, considering that the pop-up alarm will affect the actual user's online experience or work efficiency, it will generally be adopted. The following means 1 and 2 are used to suppress the client pop-up alarm:

Means 1: When the certificate is issued by the client using the self-signed certificate of the SSL proxy, the domain name/Subject/Valid of the real server is maintained in the issued certificate.

Means 2: Import the self-signed certificate as a trusted e-commerce certificate authority (CA) certificate into the client.

In combination with the foregoing means 1 and 2, when the terminal verifies the certificate issued by the SSL proxy, the terminal is considered to be a legal certificate, thereby obtaining client trust.

In the above manner, a typical information monitoring process may include the following steps as shown in FIG. 1:

1. The client initiates an SSL handshake request to the server.

2. The SSL proxy hijacks the SSL handshake request from the client;

3. The SSL proxy initiates an SSL connection request to the server;

4. The server responds to the SSL connection request initiated by the SSL proxy, and sends the server's own certificate to the SSL proxy;

5. The SSL proxy re-issues a certificate (hereinafter referred to as a newly generated certificate) using a self-signed certificate according to the certificate of the server (ie, the real server);

It can be seen from the foregoing method 2 that the client considers that the self-signed certificate used by the SSL proxy is a trusted CA certificate, so that when the subsequent client verifies the newly generated certificate, the client also issues the certificate according to the self-signed certificate. The newly generated certificate is trusted.

6. The SSL proxy pushes the newly generated certificate to the client;

7. The client uses the local trusted CA certificate to check the newly generated certificate received, and the verification passes;

8. The client requests a login page from the server;

9. The server returns a login page to the client;

10. The client sends an HTTP POST containing the login ciphertext (HTTP POST is an HTTP request);

11. The SSL proxy decrypts the HTTP POST containing the login ciphertext and obtains the clear text of the login information.

The drawback of the above solution is that the terminal is not aware of the existence of the SSL proxy, so that when the actual user of the terminal accesses the privacy or financial HTTPS website, the plaintext information such as the username and password information of the actual user is exposed to the SSL. Agents, which make this information subject to potential security threats.

Similarly, in the scenario where there is a middleman between the client and the server set in other protocol layers, the above problem also exists.

Summary of the invention

The embodiment of the present application provides a method for identifying the presence of an intermediary to solve the problem that the transmitted information may be threatened by a potential security threat because the client cannot recognize whether there is an intermediary between the client and the server.

The embodiment of the present application further provides an apparatus for identifying the presence of an intermediary to solve the problem that the transmitted information may be potentially threatened because the client cannot recognize whether there is an intermediary between the client and the server.

The embodiments of the present application adopt the following technical solutions:

A method for identifying an intermediary's presence includes: obtaining first certificate related information of a server received by a client during a handshake between a client and a server, and a non-handshake process between the client and the server The second certificate related information of the server received by the client; Whether the first certificate related information and the second certificate related information are matched.

An apparatus for identifying a presence of a middleman, comprising: an information obtaining unit, configured to obtain first certificate related information of a server received by a client during a handshake process between a client and a server, and at the client and the The second certificate related information of the server received by the client in the non-handshake process of the server; the identification unit is configured to determine whether the first certificate related information and the second certificate related information obtained by the information obtaining unit match.

The above at least one technical solution adopted by the embodiment of the present application can achieve the following beneficial effects:

When a middleman is set up, the middleman only uses his own self-signed certificate and the identity information of the server (such as domain name/Subject/Valid) in the handshake process between the client and the server to obtain a newly generated certificate, and the client The certificate-related information of the server passed during the non-handshake process with the server does not perform a similar operation, that is, the certificate-related information of the server passed during the non-handshake process is still the real certificate-related information of the server. Therefore, by comparing the handshake process and the certificate related information of the same server received during the non-handshake process, it is possible to identify whether an intermediary exists.

DRAWINGS

The drawings described herein are intended to provide a further understanding of the present application, and are intended to be a part of this application. In the drawing:

1 is a schematic diagram of an implementation principle of using a proxy technology to monitor specific information transmitted by a terminal in the prior art;

FIG. 2 is a schematic flowchart of an implementation method for identifying an existence of an intermediary according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of an implementation process of a method for preventing an intermediary attack according to Embodiment 2 of the present application;

FIG. 4 is a schematic structural diagram of an apparatus for identifying the presence of an intermediary according to Embodiment 3 of the present application.

detailed description

The technical solutions of the present application will be clearly and completely described in the following with reference to the specific embodiments of the present application and the corresponding drawings. It is apparent that the described embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present application without departing from the inventive scope are the scope of the present application.

The technical solutions provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.

Example 1

In order to solve the problem that the client cannot recognize whether there is an intermediary between the client and the server, Embodiment 1 of the present application provides a method for identifying the presence of an intermediary. The schematic diagram of the specific implementation process of the method is shown in FIG. 2, and includes the following steps:

Step 21: Obtain first certificate related information of the server received by the client during the handshake process between the client and the server, and second certificate related information of the server received by the client during the non-handshake process between the client and the server. ;

Step 22: Determine whether the first certificate related information and the second certificate related information match.

The above “certificate related information” may include the certificate itself, and may also include information closely related to the certificate, such as a hash value obtained by hashing the certificate.

With the above method provided in Embodiment 1, when an intermediary is set, the intermediary only uses its own self-signed certificate and server identity information (such as domain name/Subject/Valid information) during the handshake process between the client and the server. Obtaining a newly generated certificate, and the certificate-related information of the server passed during the non-handshake process between the client and the server does not perform a similar operation, that is, the certificate related information of the server transmitted during the non-handshake process between the client and the server is still The server's real certificate related information. Therefore, by comparing the handshake process and the certificate related information of the same server received during the non-handshake process, it is possible to identify whether an intermediary exists.

In an implementation manner, in order to enable the intermediary to obtain confidential information such as user confidential information (such as a login name and password for a server), when it is determined that the first certificate related information and the second certificate related information match, the execution may be performed. Specific operation. Here, the specific operation mentioned here includes an operation of causing an intermediary to receive confidential information.

For example, one way to perform a specific operation may include the following steps:

Display prompt information;

Receiving user instructions;

According to the user's instructions, refuse to obtain the entered confidential information, or cancel the transmission of confidential information.

The above prompt information may include text information such as "may exist an intermediary, need to guard against its attack?", and the prompt information may also include "agree to prevent" and "no need to guard against" two options.

Subsequent to receiving the user instruction triggered by the user selecting the "consume to prevent" option, the page including the confidential information input portal can be closed, thereby achieving the purpose of rejecting the input of the confidential information, thereby achieving the middleman receiving To the purpose of confidential information.

Some optional implementations of

steps

21 and 22 above are specifically described below.

For step 21, the timing of obtaining the second certificate related information of the server received during the non-handshake process between the client and the server may include: before sending the confidential information.

For example, before sending the confidential information, the second certificate related information of the server received during the non-handshake process between the client and the server may be obtained through the following sub-steps 1 to 2:

Sub-step 1: Send a confidential information page to the server to obtain a request;

The “Confidential Information Page” includes a page for inputting confidential information, such as a login page including an input portal of a user login name and a password.

Sub-step 2: Receive the confidential information page sent by the server.

The confidential information page includes information related to the second certificate.

For the step 22, in one embodiment, the verification information script may also be included in the confidential information page.

The existence of the verification script can cause the verification script to be run at the same time as the presentation of the confidential information page. The process of running the verification script, that is, the process of determining whether the first certificate related information and the second certificate related information match.

In an embodiment, when the first certificate related information includes: a certificate, and the second certificate related information includes: a hash value corresponding to the certificate (referred to as “corresponding hash value”), the specific implementation process of step 22 The following sub-step a to sub-step d may be included:

Sub-step a: hashing the first certificate related information to obtain a corresponding hash value;

Sub-step b: determining whether the corresponding hash value is the same as the obtained hash value, and performing sub-step c when the judgment result indicates that the corresponding hash value is the same as the obtained hash value; otherwise, performing sub-step d;

Sub-step c: determining that the first certificate related information and the second certificate related information match;

Sub-step d: determining that the first certificate related information and the second certificate related information do not match.

It should be noted that the execution bodies of the steps of the method provided in Embodiment 1 may all be the same device, or the method may also be performed by different devices. For example, the execution body of step 21 and step 22 may be device 1; for example, the execution body of step 21 may be device 1, the execution body of step 22 may be device 2;

Example 2

Embodiment 2 provides a method for identifying an intermediary (ie, an SSL proxy mentioned in the background section) existing in the SSL layer, thereby preventing the user from transmitting confidential information to the intermediary, thereby preventing the attack of the middleman.

The schematic diagram of the system architecture for implementing the method is similar to that of FIG. 1 and will not be described here. The following focuses on how to achieve the purpose of preventing man-in-the-middle attacks based on the system architecture.

Please refer to FIG. 3 of the specification, which is a specific implementation flowchart of the method provided in Embodiment 2. The process mainly includes the following steps:

1. The client initiates an SSL handshake request to the server.

2. The SSL proxy hijacks the SSL handshake request from the client;

3. The SSL proxy initiates an SSL connection request to the server;

6. The SSL proxy pushes the newly generated certificate to the client;

8. The client requests a login page from the server;

9. The server sends back a login page carrying the certificate related information of the server to the client;

10. The client compares the certificate-related information received from the application layer (that is, the certificate-related information of the server carried in the login page) with the newly generated certificate obtained during the SSL handshake process, and the comparison result indicates receiving from the application layer. When the certificate related information is inconsistent with the newly generated certificate, an alarm pops up, and the user selects whether to continue to log in or terminate the login.

11. The client sends an HTTP POST containing the login ciphertext.

In an embodiment, when the certificate related information carried in the login page in step 9 includes a hash value obtained by performing a hash operation on the certificate of the server, the login page may further include a verification script. After receiving the login page, the client can trigger the client to obtain the newly generated certificate obtained during the SSL handshake process, and perform a hash operation on the newly generated certificate to obtain a hash value.

Further, the client can determine whether the hash value carried in the login page matches the hash value obtained by performing a hash operation on the newly generated certificate. If not, an alarm is generated, and the user selects whether to continue the login or terminate the login. .

According to the foregoing method provided in Embodiment 2 of the present application, the method can effectively identify that an intermediary (ie, an SSL proxy) exists between the server and the client, so that the confidential information transmitted by the client can be avoided by sending an alert to the user. Subject to potential security threats from intermediaries.

Example 3

In order to solve the problem that the client in the prior art cannot recognize whether there is an intermediary between the client and the server, Embodiment 3 of the present application provides a device for identifying the presence of the intermediary. The specific structure of the device is shown in FIG. 4 . The indication includes an information obtaining unit 41 and an identifying unit 42.

The information obtaining unit 41 is configured to obtain first certificate related information of the server received by the client during the handshake process between the client and the server, and the server received by the client during the non-handshake process between the client and the server. Second certificate related information;

The identification unit 42 is configured to determine whether the first certificate related information and the second certificate related information obtained by the information obtaining unit 41 match.

In an embodiment, the information obtaining unit 41 may obtain second certificate related information of the server received during the non-handshake process between the client and the server before transmitting the confidential information.

In an embodiment, the information obtaining unit 41 may be divided into the following subunits:

a sending subunit, configured to send a confidential information page to the server to obtain a request;

The receiving subunit is configured to receive a confidential information page sent by the server.

In an embodiment, when the verification script is included in the confidential information page, the identification unit 42 may be configured to determine whether the first certificate related information and the second certificate related information match by running the verification script.

In an embodiment, if the first certificate related information includes a certificate, and the second certificate related information includes a hash value corresponding to the certificate, the identifying unit 42 may be configured to: perform hash operation on the first certificate related information, to obtain Corresponding hash value; determining whether the hash value corresponding to the certificate included in the second certificate related information is the same as the obtained hash value; if the same, determining that the first certificate related information and the second certificate related information match; If the same, it is determined that the first certificate related information and the second certificate related information do not match.

In an embodiment, the apparatus provided in Embodiment 3 of the present application may further include an operation execution unit. The operation execution unit is configured to determine, at the identification unit 42, the first certificate related information and the first When the two certificate related information matches, a specific operation is performed.

The specific operation described above may include, but is not limited to, an operation of causing an intermediary to receive confidential information.

In an embodiment, the operation execution unit may be configured to perform the following operations:

Display prompt information;

Receiving user instructions;

According to the user's instruction, the input of confidential information is rejected, or the input confidential information is denied, or the transmission of confidential information is cancelled.

When a middleman is set up, the middleman only uses his own self-signed certificate and the server's identity information (such as domain name/Subject/Valid information) during the handshake process between the client and the server to obtain a newly generated certificate, and the client is The certificate-related information of the server passed during the non-handshake process between the server and the server does not perform a similar operation, that is, the certificate-related information of the server delivered during the non-handshake process between the client and the server is still the real certificate-related information of the server. Therefore, by comparing the handshake process and the certificate related information of the same server received during the non-handshake process, it is possible to identify whether an intermediary exists.

Those skilled in the art will appreciate that embodiments of the present invention can be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or a combination of software and hardware. Moreover, the invention can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) including computer usable program code.

The present invention has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (system), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or FIG. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable information processing device to produce a machine for the execution of instructions for execution by a processor of a computer or other programmable information processing device. Implemented in flowchart one Means of a process or a plurality of processes and/or block diagrams of a function specified in a block or blocks.

The computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable information processing device to operate in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture comprising the instruction device. The apparatus implements the functions specified in one or more blocks of a flow or a flow and/or block diagram of the flowchart.

These computer program instructions can also be loaded onto a computer or other programmable information processing device such that a series of operational steps are performed on a computer or other programmable device to produce computer-implemented processing for execution on a computer or other programmable device. The instructions provide steps for implementing the functions specified in one or more of the flow or in a block or blocks of a flow diagram.

In a typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.

The memory may include non-persistent memory, random access memory (RAM), and/or non-volatile memory in a computer readable medium, such as read only memory (ROM) or flash memory. Memory is an example of a computer readable medium.

Computer readable media includes both permanent and non-persistent, removable and non-removable media. Information storage can be implemented by any method or technology. The information can be computer readable instructions, information structures, modules of programs, or other information. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory. (ROM), electrically erasable programmable read only memory (EEPROM), flash memory or other memory technology, compact disk read only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, Magnetic tape cartridges, magnetic tape storage or other magnetic storage devices or any other non-transportable media can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary storage of computer readable media, such as modulated information signals and carrier waves.

It should also be noted that the terms "including", "comprising" or "comprising" or any other variations thereof are intended to encompass a non-exclusive inclusion, such that a process, method, article, These elements are included, as well as other elements not explicitly listed, or elements that are inherent to such a process, method, commodity, or equipment. An element defined by the phrase "comprising a ..." does not exclude the presence of additional equivalent elements in the process, method, item, or device including the element.

Those skilled in the art will appreciate that embodiments of the present application can be provided as a method, system, or computer program product. Thus, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment in combination of software and hardware. Moreover, the application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) including computer usable program code.

The above description is only an embodiment of the present application and is not intended to limit the application. Various changes and modifications can be made to the present application by those skilled in the art. Any modifications, equivalents, improvements, etc. made within the spirit and scope of the present application are intended to be included within the scope of the appended claims.

Claims

A method for identifying the presence of an intermediary, characterized by comprising:

Obtaining first certificate related information received by the client during a handshake between the client and the server, and the server receiving the server by the client during a non-handshake process between the client and the server Second certificate related information;

It is determined whether the first certificate related information and the second certificate related information match.
The method according to claim 1, wherein obtaining the second certificate related information of the server received by the client during the non-handshake process between the client and the server comprises:

Before transmitting the confidential information, the second certificate related information of the server received by the client in the non-handshake process is obtained.
The method of claim 2, wherein prior to transmitting the confidential information, obtaining second certificate related information of the server received by the client during a non-handshake process between the client and the server ,include:

Sending a confidential information page acquisition request to the server;

Receiving a confidential information page sent by the server; wherein the confidential information page includes second certificate related information.
The method of claim 3, wherein the confidential information page includes a verification script;

Determining whether the first certificate related information and the second certificate related information match, including:

By running the verification script, it is determined whether the first certificate related information and the second certificate related information match.
The method according to any one of claims 1 to 4, wherein the first certificate related information comprises: a certificate; and the second certificate related information comprises: a hash value corresponding to the certificate;

Determining whether the first certificate related information and the second certificate related information match, including:

Performing a hash operation on the first certificate related information to obtain a corresponding hash value;

Determining whether the corresponding hash value is the same as the obtained hash value;

If they are the same, determining that the first certificate related information and the second certificate related information match;

If not, it is determined that the first certificate related information and the second certificate related information do not match.
The method of claim 1 wherein the method further comprises:

Performing a specific operation when it is determined that the first certificate related information and the second certificate related information match;

The specific operation includes an operation of causing an intermediary to receive no confidential information.
The method of claim 6 wherein performing a specific operation comprises:

Display prompt information;

Receiving user instructions;

The input of the confidential information is rejected according to a user instruction, or the input of the confidential information is denied, or the transmission of the confidential information is cancelled.
A device for identifying the presence of an intermediary, comprising:

An information obtaining unit, configured to obtain first certificate related information of a server received by the client during a handshake process between the client and the server, and received by the client during a non-handshake process between the client and the server The second certificate related information of the server;

The identification unit is configured to determine whether the first certificate related information and the second certificate related information obtained by the information obtaining unit match.
The device of claim 8 wherein:

And an information obtaining unit, configured to obtain second certificate related information of the server received by the client during a non-handshake process between the client and the server, before sending the confidential information.
The apparatus according to claim 9, wherein the information obtaining unit comprises:

a sending subunit, configured to send a confidential information page to the server to obtain a request;

And a receiving subunit, configured to receive a confidential information page sent by the server, where the confidential information page includes second certificate related information.
The device according to claim 10, wherein the confidential information page includes a verification script;

And an identifying unit, configured to determine, by running the verification script, whether the first certificate related information and the second certificate related information match.
The device according to any one of claims 8 to 11, wherein the first certificate related information comprises: a certificate; the second certificate related information comprises: a hash value corresponding to the certificate;

Identification unit for:

Performing a hash operation on the first certificate related information to obtain a corresponding hash value;

Determining whether the corresponding hash value is the same as the obtained hash value;

If they are the same, determining that the first certificate related information and the second certificate related information match;

If not, it is determined that the first certificate related information and the second certificate related information do not match.
The device of claim 8 further comprising:

An operation execution unit, configured to perform a specific operation when the identification unit determines that the first certificate related information and the second certificate related information match;

The specific operation includes an operation of causing an intermediary to receive no confidential information.
The device of claim 13 wherein:

The operation execution unit is configured to display the prompt information; receive the user instruction; reject the input of the confidential information according to the user instruction, or refuse to obtain the input confidential information, or cancel the transmission of the confidential information.