High

Persistence Mechanism Installation (EDR Graph)

This detection watches for files being written to the specific system locations that let a program run automatically, such as at startup or on a schedule. Attackers use these locations to make sure their malicious code survives a reboot or keeps running without further action.

How the attack works

An attacker who has already gained code execution on a machine wants their access to survive a reboot or logout. To do this they write a file into a location the operating system automatically executes: a cron job, a launchd plist (macOS), a systemd unit, or a shell profile script like .bashrc or .profile. The rule watches low-level file write activity captured by an EDR or syscall monitor and flags any write into these known persistence paths. It runs on a short interval (every 30 seconds) so the write is caught close to when it happens.

Netzilo detection

Netzilo reports this behaviour when it is observed.

Signature ID
d12c1b8c-4ee7-5548-947b-a1627bdc98dc-p
Severity
High

Why it matters

If missed, an attacker keeps a foothold on the machine indefinitely, surviving reboots, credential rotations, and casual cleanup, which extends the time they have to move laterally or exfiltrate data.

What you can do

  • Restrict write access to cron directories, systemd unit paths, launchd LaunchAgents/LaunchDaemons folders, and shell profile files to admin accounts only.
  • Review any unexpected new entries in crontabs, systemd services, launchd plists, or shell startup files as soon as they are flagged.
  • Baseline what persistence entries are expected on your systems so new or unauthorized ones stand out.
  • Treat this as one signal among others — it only detects the file write step, not how the attacker got initial access or what they did afterward.

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