Defensive-Security-System - Multithreaded Reference Monitor that maintains dat

项目说明

Defensi

Reference monitor to maintain data integrity of files

Synopsis

1. A Reference Monitor which will keep two copies of every file incase it is incorrectly written. The valid copy is used for reading and the other one is used for writing. On closing the file, if a file copy is invalid then it is discarded and if both the file copies are valid, the older one is discarded. The system was implemented using locks to support multithreading
2. The system was de using the security layer functionality in Repy V2 which is a subset of Python and tested with numerous attack cases

Rules Followed in Designing the reference monitor

1. Every `valid' file must start with the character 'S' and end with the character 'E'. If any other characters (including lowercase 's', 'e', etc.) are the first or last characters, then the file is considered invalid.
2. The system store two copies of A/B files on disk, one that is the valid backup (which is used for reading) and the other that is written to.
3. When an app calls ABopenfile(), this indicates that the A/B files, which you should name filename.a and filename.b, should be opened.
4. When the app calls readat(), all reads must be performed on the valid file. Similarly, when the app calls writeat(), all writes must be performed on the invalid file.
5. If the app uses ABopenfile() to create a file that does not exist (by setting create=True when calling ABopenfile()), the reference monitor will create a new file 'SE' in filename.a and an empty file called filename.b.
6. When close() is called on the file, if a file is not valid, it is discarded. if both files are valid, the older one is discarded.
7. It is important to keep in mind that only lowercase file names are allowed. For example:<br>
Open a file : <br>
myfile=openfile("look.txt",True) <br>
look.txt is a valid file name, however Look.txt and LOOK.TXT are not. Examples of other invalid files names are, _look.txt, look/.txt, and look().txt. Essentially all non-alphanumeric characters are not allowed.
8. The reference monitor must not any unexpected errors or produce any output i.e. should not log anything.
##### Note : The behavior of other file system calls should remain unchanged. This means listfiles(), remo(), and calls to files accessed with openfile() instead of ABopenfile() remain unchanged by this reference monitor.
#### Design Paradigms considered
1. Accuracy: The security layer should only stop certain actions from being blocked. All other actions should be allowed. For example, if an app tries to read data from a valid file, this must succeed as per normal and must not be blocked. All situations that are not described above must match that of the underlying API.
2. Efficiency: The security layer should use a minimum number of resources, so performance is not compromised. For example, keeping a complete copy of every file on disk in memory would be forbidden.
3. Security: The attacker should not be able to circumvent the security layer. Hence, if the attacker can cause an invalid file to be read or can write to a valid file, then the security is compromised, for example.

Attack Case Explanation

1. Attack Case 1 : It checks if valid data write to a file is successful i.e. checks if the accuracy of the system is not compromised.
2. Attack Case 2 : It checks if an existing file is reopened successfully i.e checks if the accuracy of the system is not compromised.
3. Attack Case 3 : It checks if the system prevents saving of invalid data in a file when the file is closed i.e. checks if the security of the system is not compromised.
4. Attack Case 4 : It checks if the empty file condition of writing valid data SE by default in a file is satisfied when a new file is created i.e. checks if the accuracy of the system is not compromised.
5. Attack Case 5 : It checks if data is read from the valid copy/data is written into the other copy when valid data is written and the file is not closed i.e. checks if the security of the system is not compromised.
6. Attack Case 6 : It checks if data is read from the valid copy/data is written into the other copy when invalid data is written and the file is not closed i.e. checks if the security of the system is not compromised.
7. Attack Case 7 : It checks if the system is allowing to perform a simple write operation i.e. checks if the accuracy of the system is not compromised.
8. Attack Case 8 : It checks if the system is allowing to perform a simple read operation i.e. checks if the accuracy of the system is not compromised.
9. Attack Case 9 : It checks if the system handles writing in multiple files simultaneously i.e. checks if the accuracy of the system is not compromised.
10. Attack Case 10 : It checks if the system handles writing in multiple files simultaneously i.e. checks if the accuracy of the system is not compromised.

How to Setup

1. Please refer to the below link for details on how to setup Repy V2 <br>
<a href= " V2 Setup</a><br>
2. Once you ha RepyV2 into a directory of your choice, change into that directory. Use the command below in order to run your RepyV2 programs:<br>
python repy.py restrictions.default encasementlib.r2py [security_layer].r2py [program].r2py <br>
(Replace [security_layer].r2py and [program].r2py by the names of the Reference Monitor and Attack Case that you want to run.)
##### Note :repy.py, restrictions.default, encasementlib.r2py, the security layer and the program you want to run should be in the same current working directory.
3. It is possible to add multiple security layers and Attack Cases to Repy, this may be useful for testing multiple security layers against multiple test cases. This is done with the following command at the terminal:<br>
for referencemonitor in reference_monitor_*; do for testcase in <attack_case>_*; do python repy.py restrictions.default encasementlib.r2py $referencemonitor $testcase; done; done
##### Note : All reference monitor names should start with the word reference_monitor_ and all Attack Cases should also start with same letters which replace <attack_case> in the abo.The abo will print out the output from each attack case.
4. If you want to spot the referencemonitor that failed during the test run, add echo the name of each referencemonitor before the inner loop, like so:<br>
for referencemonitor in reference_monitor_*; do echo $referencemonitor under test; for testcase in <attack_case>_*; do python repy.py restrictions.default encasementlib.r2py $referencemonitor $testcase; done; done
##### Note : The abo will print out the name of each reference monitor before it starts executing the attack case against it.
5. Some important references to learn Repy V2 <br>
<a href = " Repy V2 Syntax</a><br>
<a href = " V2 </a>
##### Note :In repy log replaces print from python.

项目信息

开发语言：未知

Star 数：5

技术要点

该项目属于防护思路方向的开源资源，代码结构清晰，适合安全研究人员学习参考。项目围绕Multithreaded Reference Monitor that maintains data integrity of files in file system 展开，提供了可运行的实现，对理解相关安全机制、工具原理与攻防技术具有较高的研究价值。

从技术实现角度看，此类项目的核心在于对底层原理的深入理解与工程化落地。开发者在研究过程中可以结合官方文档与社区讨论，梳理项目的初始化流程、核心模块职责与数据流转，逐步掌握其中的技术细节与设计思路。

使用与学习建议

1. 下载源码压缩包，解压到本地环境。

2. 根据项目类型准备对应的运行环境与依赖。

3. 按照 README 中的步骤完成配置与部署。

4. 在隔离的测试环境中运行验证，避免影响生产系统。

免责声明

本资源来源于开源社区，仅供安全研究、技术学习与合法授权范围内的攻防演练使用，请勿用于任何非法或侵害他人权益的用途。使用本项目产生的一切后果由使用者自行承担。