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
AppStreamrepository is enabled.
Procedure
Install the
aidepackage:# yum install aideGenerate an initial database:
# 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==-
Optional: In the default configuration, the
aide --initcommand checks just a set of directories and files defined in the/etc/aide.conffile. To include additional directories or files in the AIDE database, and to change their watched parameters, edit/etc/aide.confaccordingly. To start using the database, remove the
.newsubstring from the initial database file name:# mv /var/lib/aide/aide.db.new.gz /var/lib/aide/aide.db.gz-
Optional: To change the location of the AIDE database, edit the
/etc/aide.conffile and modify theDBDIRvalue. For additional security, store the database, configuration, and the/usr/sbin/aidebinary 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:
# 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 …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
croncommand, add the following line to the/etc/crontabfile:05 4 * * * root /usr/sbin/aide --check
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:
# aide --updateThe
aide --updatecommand creates the/var/lib/aide/aide.db.new.gzdatabase file.-
To start using the updated database for integrity checks, remove the
.newsubstring 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.
| 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. |
