Query: detection rule: Detects the removal of system firewall rules. Adversaries may only delete or modify a specific system firewall rule to b
Matching passage: Sigma rule: Detects the removal of system firewall rules. Adversaries may only delete or modify a specific system firewall rule to b. Logsource: linux / auditd. Rule: title: Modify System Firewall id: 323ff3f5-0013-4847-bbd4-250b5edb62cc related: - id: 53059bc0-1472-438b-956a-7508a94a91f0 type: similar status: test description: 'Detects the removal of system firewall rules. Adversaries may only delete or modify a specific system firewall rule to bypass controls limiting network usage or access. Detection rules that match only on the disabling of firewalls will miss this. ' references: - https://www.trendmicro.com/en_us/research/22/c/cyclops-blink-sets-sights-on-asus-routers--.html - https://blog.aquasec.com/container-security-tnt-container-attack - https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/html/configuring_and_managing_networking/getting-started-with-nftables_configuring-and-managing-networking author: IAI date: 2023-03-06 modified: 2025-10-12 tags: - attack.defense-impairment - attack.t1686 logsource: product: linux service: auditd detection: selection1: type: EXECVE a0: iptables a1|contains: DROP selection2: type: EXECVE a0: firewall-cmd a1|contains: remove selection3: type: EXECVE a0: ufw a1|contains: delete selection4: type: EXECVE a0: nft a1|contains: - delete - flush condition: 1 of selection* falsepositives: - Legitimate admin activity level: medium
Near-miss passage: Sigma rule: Detects when the Notepad++ updater (gup.exe) makes DNS queries to domains that are not part of the known legitimate upda. Logsource: windows / dns_query. Rule: title: Notepad++ Updater DNS Query to Uncommon Domains id: 2074e137-1b73-4e2d-88ba-5a3407dbdce0 status: experimental description: 'Detects when the Notepad++ updater (gup.exe) makes DNS queries to domains that are not part of the known legitimate update infrastructure. This could indicate potential exploitation of the updater mechanism or suspicious network activity that warrants further investigation. ' references: - https://notepad-plus-plus.org/news/v889-released/ - https://www.heise.de/en/news/Notepad-updater-installed-malware-11109726.html - https://www.rapid7.com/blog/post/tr-chrysalis-backdoor-dive-into-lotus-blossoms-toolkit/ - https://www.validin.com/blog/exploring_notepad_plus_plus_network_indicators/ - https://securelist.com/notepad-supply-chain-attack/118708/ author: Swachchhanda Shrawan Poudel (Nextron Systems) date: 2026-02-02 modified: 2026-03-16 tags: - attack.collection - attack.credential-access - attack.t1195.002 - attack.initial-access - attack.t1557 logsource: category: dns_query product: windows detection: selection: Image|endswith: \gup.exe filter_main_notepad_legit_domain: QueryName: notepad-plus-plus.org filter_optional_sourceforge_legit_domain: QueryName|endswith: .sourceforge.net filter_optional_github_legit_domain: - QueryName|endswith: .githubusercontent.com - QueryName: github.com filter_optional_google_storage_legit_domain: QueryName|endswith: .googleapis.com filter_optional_uncommon_domains: QueryName|endswith: - .azurewebsites.net - block.opendns.com - gateway.zscalerthree.net condition: selection and not 1 of filter_main_* and not 1 of filter_optional_* falsepositives: - Some legitimate network misconfigurations or proxy issues causing unexpected DNS queries. - Other legitimate query to official domains not listed in the filter, needing tuning. level: medium