Query: EDR alert: possible Systemd Timers (T1053.006)
Matching passage: T1053.006 Systemd Timers. Tactics: execution, persistence, privilege escalation. Description: Adversaries may abuse systemd timers to perform task scheduling for initial or recurring execution of malicious code. Systemd timers are unit files with file extension <code>.timer</code> that control services. Timers can be set to run on a calendar event or after a time span relative to a starting point. They can be used as an alternative to [Cron](https://attack.mitre.org/techniques/T1053/003) in Linux environments.(Citation: archlinux Systemd Timers Aug 2020) Systemd timers may be activated remotely via the <code>systemctl</code> command line utility, which operates over [SSH](https://attack.mitre.org/techniques/T1021/004).(Citation: Systemd Remote Control) Each <code>.timer</code> file must have a corresponding <code>.service</code> file with the same name, e.g., <code>example.timer</code> and <code>example.service</code>. <code>.service</code> files are [Systemd Service](https://attack.mitre.org/techniques/T1543/002) unit files that are managed by the systemd system and service manager.(Citation: Linux man-pages: systemd January 2014) Privileged timers are written to <code>/etc/systemd/system/</code> and <code>/usr/lib/systemd/system</code> while user level are written to <code>~/.config/systemd/user/</code>. An adversary may use systemd timers to execute malicious code at system startup or on a scheduled basis for persistence.(Citation: Arch Linux Package Systemd Compromise BleepingComputer 10JUL2018)(Citation: gist Arch package compromise 10JUL2018)(Citation: acroread package compromised Arch Linux Mail 8JUL2018) Timers installed using privileged paths may be used to maintain root level persistence. Adversaries may also install user level timers to achieve user level persistence.(Citation: Falcon Sandbox smp: 28553b3a9d)
Near-miss passage: T1053.002 At. Tactics: execution, persistence, privilege escalation. Description: Adversaries may abuse the [at](https://attack.mitre.org/software/S0110) utility to perform task scheduling for initial or recurring execution of malicious code. The [at](https://attack.mitre.org/software/S0110) utility exists as an executable within Windows, Linux, and macOS for scheduling tasks at a specified time and date. Although deprecated in favor of [Scheduled Task](https://attack.mitre.org/techniques/T1053/005)'s [schtasks](https://attack.mitre.org/software/S0111) in Windows environments, using [at](https://attack.mitre.org/software/S0110) requires that the Task Scheduler service be running, and the user to be logged on as a member of the local Administrators group. In addition to explicitly running the `at` command, adversaries may also schedule a task with [at](https://attack.mitre.org/software/S0110) by directly leveraging the [Windows Management Instrumentation](https://attack.mitre.org/techniques/T1047) `Win32_ScheduledJob` WMI class.(Citation: Malicious Life by Cybereason) On Linux and macOS, [at](https://attack.mitre.org/software/S0110) may be invoked by the superuser as well as any users added to the <code>at.allow</code> file. If the <code>at.allow</code> file does not exist, the <code>at.deny</code> file is checked. Every username not listed in <code>at.deny</code> is allowed to invoke [at](https://attack.mitre.org/software/S0110). If the <code>at.deny</code> exists and is empty, global use of [at](https://attack.mitre.org/software/S0110) is permitted. If neither file exists (which is often the baseline) only the superuser is allowed to use [at](https://attack.mitre.org/software/S0110).(Citation: Linux at) Adversaries may use [at](https://attack.mitre.org/software/S0110) to execute programs at system startup or on a scheduled basis for [Persistence](https://attack.mitre.org/tactics/TA0003). [at](https://attack.mitre.org/software/S0110) can also be abused to conduct remote [Execution](https://attack.mitre.org/tactics/TA0002) as part of [Lateral Move