Audisp-json |
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Table of contents |
This program is a plugin for Linux Audit user space programs available at <http://people.redhat.com/sgrubb/audit/>. |
It uses the audisp multiplexer. |
Audisp-json correlates messages coming from the kernel's audit (and through audisp) into a single JSON message that is |
sent directly to a log server (it doesn't use syslog). |
The JSON format used is MozDef message format. |
Regular audit log messages and audisp-json error, info messages still use syslog. |
Due to the ring buffer filling up when the front-end HTTP server does not process fast enough, the program may slowly |
grow in memory for a while on busy systems. It'll stop at 512 messages (hard-coded) buffered. |
Building |
Required dependencies: |
- Audit (2.0+) |
- libtool |
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For package building: |
- FPM |
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Build targets: |
============= |
They're self explanatory. |
- make |
- make rpm |
- make deb |
- make install |
- make uninstall |
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Mozilla build targets |
===================== |
We previously used audisp-cef, so we would want to mark that package as obsolete. |
- make rpm FPMOPTS="--replaces audisp-cef" |
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Deal with auditd quirks, or how to make auditd useable in prod |
These examples filter out messages that may clutter your log or/and DOS yourself (high I/O) if auditd goes |
down for any reason. |
Example for rsyslog |
#Drop native audit messages from the kernel (may happen is auditd dies, and may kill the system otherwise) :msg, regex, "type=[0-9]* audit" ~ #Drop audit sid msg (work-around until RH fixes the kernel - should be fixed in RHEL7 and recent RHEL6) :msg, contains, "error converting sid to string" ~
source s_syslog { unix-dgram("/dev/log"); }; filter f_not_auditd { not message("type=[0-9]* audit") or not message("error converting sid to string"); }; log{ source(s_syslog);f ilter(f_not_auditd); destination(d_logserver); };
- It is suggested to bump the audispd queue to adjust for extremely busy systems, for ex. q_depth=512.
- You will also probably need to bump the kernel-side buffer and change the rate limit in audit.rules, for ex. -b 16384 -r 500.
Syscalls are interpreted by audisp-json and transformed into a MozDef JSON message. This means, for example, all execve() and related calls will be aggregated into a message of type EXECVE.
Supported messages are listed in the document messages_format.rst
The audisp-json.conf file has 4 options:
- mozdef_url
Any server supporting JSON MozDef messages
- ssl_verify
Yes or no. Only use no for testing purposes.
- curl_verbose
Enables curl verbose mode for debugging. start audisp-json in the foreground to see messages.
- curl_logfile
Path to a file to log curl debug messages to. Most useful with curl_verbose also set. Otherwise, message go to stderr.
- curl_cainfo
Specify the path to a single CA certificate, if needed. When not specified, system's CA bundle is used.