Query: Sigma YAML for linux / file_event
Matching passage: Sigma rule: Detects the creation of cron files in Cron directories, which could indicate potential persistence mechanisms being esta. Logsource: linux / file_event. Rule: title: New Cron File Created id: 6c4e2f43-d94d-4ead-b64d-97e53fa2bd05 status: experimental description: 'Detects the creation of cron files in Cron directories, which could indicate potential persistence mechanisms being established by an attacker. Note that not all cron file creations are malicious - legitimate system administration activities and software installations may also create cron files. This detection should be investigated in context, considering factors such as the user creating the file, the timing of creation, and the contents of the cron job. Focus investigation on unexpected cron files created by non-administrative users or during suspicious timeframes. Additionally, it is recommended to review the contents of the newly created cron files to assess their intent. Furthermore, it is suggested to baseline normal cron file creation and apply additional filters to reduce false positives based on the specific environment. ' references: - https://github.com/microsoft/MSTIC-Sysmon/blob/f1477c0512b0747c1455283069c21faec758e29d/linux/configs/attack-based/persistence/T1053.003_Cron_Activity.xml - https://pberba.github.io/security/2022/01/30/linux-threat-hunting-for-persistence-systemd-timers-cron/ - https://www.elastic.co/security-labs/primer-on-persistence-mechanisms - https://snehbavarva.medium.com/privilege-escalation-techniques-series-linux-cron-jobs-a5b797b424b4 author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), MSTIC date: 2021-10-15 modified: 2026-04-28 tags: - attack.privilege-escalation - attack.execution - attack.persistence - attack.t1053.003 logsource: product: linux category: file_event detection: selection_cron_dirs: TargetFilename|startswith: - /etc/cron.d/ - /etc/cron.daily/ - /etc/cron.hourly/ - /etc/cron.monthly/ - /etc/cron.weekly/ - /var/spool/cron/crontabs/ - /var/spool/cron/root selection_cron_special_files: TargetFilename|contains: - /etc/cron.allow - /etc/cron.deny - /etc/crontab filter_optional_legit_cron: TargetFilename: - /etc/cron.daily/apt - /etc/cron.daily/dpkg - /etc/cron.daily/passwd - /etc/crontabs/root condition: 1 of selection_* and not 1 of filter_optional_* falsepositives: - Legitimate administrative tasks, package managers, containers, configuration management tools, cloud agents, or system maintenance operations might cause false positives. Apply baselining before deployment. level: low
Near-miss passage: Sigma rule: Detects the execution of "dotnet-dump" with the "collect" flag. The execution could indicate potential process dumping o. Logsource: windows / process_creation. Rule: title: Process Memory Dump Via Dotnet-Dump id: 53d8d3e1-ca33-4012-adf3-e05a4d652e34 status: test description: 'Detects the execution of "dotnet-dump" with the "collect" flag. The execution could indicate potential process dumping of critical processes such as LSASS. ' references: - https://learn.microsoft.com/en-us/dotnet/core/diagnostics/dotnet-dump#dotnet-dump-collect - https://twitter.com/bohops/status/1635288066909966338 author: Nasreddine Bencherchali (Nextron Systems) date: 2023-03-14 tags: - attack.stealth - attack.t1218 logsource: category: process_creation product: windows detection: selection_img: - Image|endswith: \dotnet-dump.exe - OriginalFileName: dotnet-dump.dll selection_cli: CommandLine|contains: collect condition: all of selection_* falsepositives: - Process dumping is the expected behavior of the tool. So false positives are expected in legitimate usage. The PID/Process Name of the process being dumped needs to be investigated level: medium