![]() Adversaries can add an entry in /etc/at.allow, which is a list of users allowed to execute the “at” command. If an attacker already has reverse shell access, it can also modify these normal tasks by using editor or by using “crontab -e” command to add crontab entry in existing scheduled tasks. This can be done with simple echo and stdout pipe technique like in the code block below.Įcho "/tmp/evil_cron.sh" > /etc/cron.daily/logrotate echo "/tmp/evil_cron.sh" > /etc/cron.hourly/logrotate echo "/tmp/evil_cron.sh" > /etc/cron.monthly/logrotate echo "/tmp/evil_cron.sh" > /etc/cron.weekly/logrotate This code will successfully execute with cron job privileges, allowing the attackers to escalate privileges.Īnother technique is modifying normal cron job scripts by appending malicious script code within it to hide its track from detection and analysis. If known cron jobs directories are writable, an attacker may drop a malicious script or binaries on those folders to automatically execute their code. This utility is commonly abused by adversaries to execute their malicious code periodically depending on its designed schedule. “At”, cron jobs also known as crontabs are a command-line utility on UNIX OS to schedule a job or task to run specific script or binary periodically, on fixed times or with intervals. Let’s discuss a high-level overview of this analytic story that introduced 32 new detections. We recommend you to read, install this tool as well as the splunk sysmon TA’s for this analytics.Īnalytic stories are full security use cases supported by our threat research team’s pre-built detections and responses. We used sysmon linux as the main event logs collection for our detection development. The following analytics are designed for the Linux OS platform. These techniques commonly overlap or partner with persistence techniques in elevated context. Privilege Escalation is the tactic where adversaries attempt to gain elevated or higher-level privileges for their malicious code to take advantage of root or admin privileges. Persistence consists of different techniques for adversaries or malware authors to maintain their foothold and access on the targeted or compromised system during boot-up, restart of machine or even during credential change. ![]() This article will be the deep dive part of our January 2022 release blog. In this blog article, we will do a deep dive on some popular techniques and detections for these two tactics. The Splunk Threat Research Team added Linux Privilege Escalation and Linux Persistence Techniques analytic stories to help Security Operations Center (SOC) Analysts and Security Researchers detect adversaries or malware using these techniques within the Linux OS platform.
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