Scheduled Task/Job: Cron T1053.003
Tactics: Execution, Persistence, Privilege Escalation
Adversaries may abuse the cron utility to perform task scheduling for initial or recurring execution of malicious code. The cron utility is a time-based job scheduler for Unix-like operating systems. The crontab file contains the schedule of cron entries to be run and the specified times for execution. Any crontab files are stored in operating system-specific file paths.
Events covered
4 catalog events are tagged with this technique by at least one rule.
| Provider | Event | Title |
|---|---|---|
| ESF | exec | Process Execution (Notify) |
| ESF | write | File Write (NOTIFY) |
| Sysmon-for-Linux | Event ID 1 | Process Create |
| Sysmon-for-Linux | Event ID 11 | File created |
Authoring guide
Patterns shared across the 29 rules above: which fields they filter on, what specific values they look for, and what they exclude. The catalog normalizes field names across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.
Fields filtered most (32 distinct)
The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.
Top indicator values (434 distinct)
Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique. Click a value to expand the rules under this technique that use it.
Exclusions (194 distinct)
Field/operator/value combinations excluded by rules under this technique (top-level not() clauses), sorted by how many rules exclude each. These are the false-positive paths the community has learned to filter out. A new rule that ignores the high-count entries here will likely fire on the same noisy paths. Click a value to expand the rules under this technique that exclude it.
Rules under this technique
Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.
Sigma 6 rules
- Azure Kubernetes CronJob
- Modifying Crontab
- New Cron File Created
- Scheduled Cron Task/Job - Linux
- Scheduled Cron Task/Job - MacOs
- Triple Cross eBPF Rootkit Default Persistence
Elastic 11 rules
- Cron Job Created or Modified
- Executable Bit Set for Potential Persistence Script
- Modification of Persistence Relevant Files Detected via Defend for Containers
- Pod or Container Creation with Suspicious Command-Line
- Potential Persistence via File Modification
- Potential Persistence via Periodic Tasks
- Privilege Escalation via Root Crontab File Modification
- Suspicious CronTab Creation or Modification
- Suspicious Echo or Printf Execution Detected via Defend for Containers
- Suspicious Execution from Foomatic-rip or Cupsd Parent
- Suspicious Network Activity to the Internet by Previously Unknown Executable
Splunk 10 rules
- Cisco Isovalent - Cron Job Creation
- Cisco Secure Firewall - Wget or Curl Download
- Linux Add Files In Known Crontab Directories
- Linux Adding Crontab Using List Parameter
- Linux At Allow Config File Creation
- Linux Auditd Edit Cron Table Parameter
- Linux Auditd Possible Append Cronjob Entry On Existing Cronjob File
- Linux Edit Cron Table Parameter
- Linux Possible Append Cronjob Entry on Existing Cronjob File
- Linux Possible Cronjob Modification With Editor