# A Framework for Attribute-Based Access Control in Processing Big Data with Multiple Sensitivities
## 2 Materials and Methods
### Cybersecurity Vulnerability Evaluation
#### 2.2.1 Access Control for Hadoop Distributed File System  
The HDFS stores data in files and folders by breaking them into blocks and tracking the location of the storage block in the FSImage and editLogs files. The default size of a data block is 128 MB, and this is configurable. These blocks are replicated, typically three times, to avoid data loss and support high availability. The permission settings for files and folders in HDFS are based on the POSIX model. However, there are certain differences because there is no concept of executable files, i.e., program files are stored outside the HDFS. If the HDFS is configured to conduct permissions, check for a file or directory accessed by a client process, and the traditional, owner, group, and other permissions are checked. If a file permissions check fails, the client operation fails regardless of whether it is a simple command-line interface request or a job execution. If the property in the core-site.xml file is not set to check authorizations, only the account under which Hadoop is run, i.e., the Hadoop superuser account, can access the files and directories. In this situation, proxy servers are typically used to map all permitted users to the privileged superuser. The contents of the file system and the status of block replication in the Data Nodes are displayed through a web browser-based graphical user interface (WebUI). This interface, as well as all HDFS files, reads, and writes, can be executed over the Secure Socket Layer (SSL)/Transport Layer Security (TLS) if configured. By default, Hadoop exchanges data in \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Access Control (AC)** & **Vulnerabilities** & **Threats** \\ \hline \multirow{2}{*}{Hadoop File System (HDFS)} & File system ACs are turned off by default and can be configured in multiple ways & Unauthorized reading and writing to HDFS \\ \cline{2-3}  & SSL/TLS protections on the HDFS WebUI are not enabled by default and can be configured as optional & Man-in-the-middle observation of file system file/folder names, contents, and permissions \\ \hline \multirow{2}{*}{Operating System (OS) and Directory Services} & OS, Directory, and Hadoop AC configured and managed independently & Misconfigured AC can lead to overly permissive or restrictive access \\ \cline{2-3}  & Disabled host firewalls and SELinux & Reconnaissance scanning by using NMap, OpenVAS, and other port scanners identifies open ports, protocols, and services leading to unauthorized connections and malware or beacon implants \\ \hline \multirow{2}{*}{Resource Management, YARN scheduling jobs and consume processing resources} & Optional configuration of AC lists on job scheduling queues/pools allows all to submit jobs and consume processing resources & Unauthorized job submissions that hijack cluster resources, such as cryptocurrency miner implants and DemonBot \\ \cline{2-3}  & Proxy servers reuse superuser accounts to prioritize job execution & Submitting malicious jobs, such as ransomware, that encrypt and delete files \\ \hline \multirow{2}{*}{Service-level Authorizations} & Externally exposed wide port range for RPC and HTTP protocols & Web application attacks, such as cross-site scripting \\ \cline{2-3}  & Reverse shell implants through open & \\ \cline{2-3}  & Unauthenticated SQL interfaces to the data storage (JDBC) & SQL injection attacks that corrupt or delete data \\ \hline \multirow{2}{*}{Management Controls} & Different management consoles to multiple ecosystem tools using various ports and login credentials & Attacks are undetected owing to insufficient visibility of the management of system configuration and analysis of logs \\ \cline{2-3}  & Multiple configuration and log files distributed throughout the cluster that contain sensitive information, such as privileged accounts and passwords. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Hadoop AC areas, vulnerabilities in the attack path, and patterns of threats posed by attacks. clear text.