Query: Sigma rule for Detects the attempt to install new skills for AI agents using the "npx skills" command. Agent skills enhance AI agents w
Matching passage: Sigma rule: Detects the attempt to install new skills for AI agents using the "npx skills" command. Agent skills enhance AI agents w. Logsource: windows / process_creation. Rule: title: New Agent Skills Installation Attempt Via Node.EXE id: afa71271-6a97-4e47-810f-83120fb1a4ce status: experimental description: 'Detects the attempt to install new skills for AI agents using the "npx skills" command. Agent skills enhance AI agents with new capabilities, but attackers may abuse this mechanism to inject malicious commands executed by the agent on behalf of the user. The "npx skills" command can install skills for various agents (e.g., Claude Code, Cursor, and others). Analysts should review any installed skills to verify their legitimacy. Note: Tune this rule based on whether AI agent tooling is allowed in your environment. In environments where such tooling is authorized, this detection may reflect normal activity and the alert level should be adjusted accordingly. In environments where AI agent tooling is not permitted, this activity is likely suspicious and may require immediate investigation. ' references: - https://blog.lukaszolejnik.com/supply-chain-risk-of-agentic-ai-infecting-infrastructures-via-skill-worms/ - https://github.com/vercel-labs/skills/blob/1f7fbc8d0e49c4e0601d364696bd1bdd15e80967/README.md - https://opensourcemalware.com/blog/clawdbot-skills-ganked-your-crypto - https://promptintel.novahunting.ai/molt author: Marco Pedrinazzi (@pedrinazziM) (InTheCyber) date: 2026-02-03 tags: - attack.execution - attack.t1059.007 logsource: product: windows category: process_creation detection: selection_img: - Image|endswith: \node.exe - OriginalFileName: node.exe selection_cli: CommandLine|contains|all: - npx-cli.js - 'skills ' - ' add ' condition: all of selection_* falsepositives: - This rule will be triggered when a new agent skill is installed regardless if it is benign or malicious. - High false positive rate expected in environments where AI agent tooling is authorized and commonly used. level: medium regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_node_new_agent_skills_installed/info.yml
Near-miss passage: Sigma rule: Detects execution of "curl.exe" with a potential custom "User-Agent". Attackers can leverage this to download or exfiltr. Logsource: windows / process_creation. Rule: title: Curl Web Request With Potential Custom User-Agent id: 85de1f22-d189-44e4-8239-dc276b45379b status: test description: Detects execution of "curl.exe" with a potential custom "User-Agent". Attackers can leverage this to download or exfiltrate data via "curl" to a domain that only accept specific "User-Agent" strings references: - https://labs.withsecure.com/publications/fin7-target-veeam-servers - https://github.com/WithSecureLabs/iocs/blob/344203de742bb7e68bd56618f66d34be95a9f9fc/FIN7VEEAM/iocs.csv author: Nasreddine Bencherchali (Nextron Systems) date: 2023-07-27 modified: 2025-12-11 tags: - attack.execution logsource: category: process_creation product: windows detection: selection_img: - Image|endswith: \curl.exe - OriginalFileName: curl.exe selection_header_flag_1: CommandLine|re: \s-H\s selection_header_flag_2: CommandLine|contains: --header selection_user_agent: CommandLine|contains: 'User-Agent:' condition: selection_img and 1 of selection_header_* and selection_user_agent falsepositives: - Unknown level: medium regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_curl_custom_user_agent/info.yml