Chapter 7. Checking integrity with AIDE Advanced Intrusion Detection Environment (AIDE) is a utility that creates a database of files on the system, and then uses that database to ensure file integrity and detect system intrusions. 7.1. Installing AIDE To start file-integrity checking with AIDE, you must install the corresponding package and initiate the AIDE database. Prerequisites The AppStream repository is enabled. Procedure Install the aide package: Generate an initial database: Optional: In the default configuration, the aide --init command checks just a set of directories and files defined in the /etc/aide.conf file. To include additional directories or files in the AIDE database, and to change their watched parameters, edit /etc/aide.conf accordingly. To start using the database, remove the .new substring from the initial database file name: Optional: To change the location of the AIDE database, edit the /etc/aide.conf file and modify the DBDIR value. For additional security, store the database, configuration, and the /usr/sbin/aide binary file in a secure location such as a read-only media. 7.2. Performing integrity checks with AIDE You can use the crond service to schedule regular file-integrity checks with AIDE. Prerequisites AIDE is properly installed and its database is initialized. See Installing AIDE Procedure To initiate a manual check: At a minimum, configure the system to run AIDE weekly. Optimally, run AIDE daily. For example, to schedule a daily execution of AIDE at 04:05 a.m. by using the cron command, add the following line to the /etc/crontab file: Additional resources cron(8) man page on your system 7.3. Updating an AIDE database After verifying the changes of your system, such as package updates or configuration files adjustments, update also your baseline AIDE database. Prerequisites AIDE is properly installed and its database is initialized. See Installing AIDE Procedure Update your baseline AIDE database: The aide --update command creates the /var/lib/aide/aide.db.new.gz database file. To start using the updated database for integrity checks, remove the .new substring from the file name. 7.4. File-integrity tools: AIDE and IMA Red Hat Enterprise Linux provides several tools for checking and preserving the integrity of files and directories on your system. The following table helps you decide which tool better fits your scenario. Table 7.1. Comparison between AIDE and IMA Question Advanced Intrusion Detection Environment (AIDE) Integrity Measurement Architecture (IMA) What AIDE is a utility that creates a database of files and directories on the system. This database serves for checking file integrity and detect intrusion detection. IMA detects if a file is altered by checking file measurement (hash values) compared to previously stored extended attributes. How AIDE uses rules to compare the integrity state of the files and directories. IMA uses file hash values to detect the intrusion. Why Detection - AIDE detects if a file is modified by verifying the rules. Detection and Prevention - IMA detects and prevents an attack by replacing the extended attribute of a file. Usage AIDE detects a threat when the file or directory is modified. IMA detects a threat when someone tries to alter the entire file. Extension AIDE checks the integrity of files and directories on the local system. IMA ensures security on the local and remote systems. 7.5. Additional resources aide(1) man page on your system Kernel integrity subsystem

Commands:
yum install aide
aide --init Start timestamp: 2024-07-08 10:39:23 -0400 (AIDE 0.16) AIDE initialized database at /var/lib/aide/aide.db.new.gz Number of entries: 55856 --------------------------------------------------- The attributes of the (uncompressed) database(s): --------------------------------------------------- /var/lib/aide/aide.db.new.gz ... SHA512 : mZaWoGzL2m6ZcyyZ/AXTIowliEXWSZqx IFYImY4f7id4u+Bq8WeuSE2jasZur/A4 FPBFaBkoCFHdoE/FW/V94Q==
mv /var/lib/aide/aide.db.new.gz /var/lib/aide/aide.db.gz
aide --check Start timestamp: 2024-07-08 10:43:46 -0400 (AIDE 0.16) AIDE found differences between database and filesystem!! Summary: Total number of entries: 55856 Added entries: 0 Removed entries: 0 Changed entries: 1 --------------------------------------------------- Changed entries: --------------------------------------------------- f ... ..S : /root/.viminfo --------------------------------------------------- Detailed information about changes: --------------------------------------------------- File: /root/.viminfo SELinux : system_u:object_r:admin_home_t:s | unconfined_u:object_r:admin_home 0 | _t:s0 ...
05 4 * * * root /usr/sbin/aide --check
aide --update