Anthropic Cybersecurity Skills is a library of structured cybersecurity procedures for AI agents, covering security domains and mappings to established security frameworks. It is for authorized security analysis, penetration testing, incident response, research, defense, and education across compatible AI platforms. The catalogue entries package parts of this library as agent skills, instructions, or a plugin.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill analyzing-linux-audit-logs-for-intrusiongit clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-SkillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/mukul975/anthropic-cybersecurity-skills/analyzing-linux-audit-logs-for-intrusion)<a href="https://agentmods.dev/skills/mukul975/anthropic-cybersecurity-skills/analyzing-linux-audit-logs-for-intrusion"><img src="https://agentmods.dev/badge/skills/mukul975/anthropic-cybersecurity-skills/analyzing-linux-audit-logs-for-intrusion/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/mukul975/anthropic-cybersecurity-skills/analyzing-linux-audit-logs-for-intrusion"><img src="https://agentmods.dev/badge/skills/mukul975/anthropic-cybersecurity-skills/analyzing-linux-audit-logs-for-intrusion.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk warn
- NVIDIA SkillSpector warn
SkillSpector: 11 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Privilege Escalation · line 44 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 89 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 44 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 90 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 150 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 151 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 273 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 97 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high YARA Match · line 124 YARA rule matched a known malware signature (reverse shell, backdoor, ransomware, C2 framework, or info stealer).Fix: Remove the malware payload or compromised file entirely. Investigate how it entered the skill and audit all other artifacts for additional indicators of compromise.
- medium Privilege Escalation · line 51 Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
- medium Privilege Escalation · line 153 Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00093 | $0.02656 |
| Opus 5 | $0.00046 | $0.01328 |
| Sonnet 5 | $0.00019 | $0.00531 |
| Haiku 4.5 | $0.00009 | $0.00266 |
Grade B, and why
analyzing-linux-audit-logs-for-intrusion scanned grade B with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Asks for rootlowPrivilege escalation
A mod that escalates privileges can change anything on the machine, not only the project.
- Root or sudo access to configure audit rules and query logs Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
Reaches for credential filesmediumPrivilege escalation
SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.
-w /root/.ssh/authorized_keys -p wa -k ssh_key_tampering Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
Copies of this mod
7 near-identical copies found in the catalogue:
- analyzing-linux-audit-logs-for-intrusion — 100% identical, 0 lines differ
- analyzing-linux-audit-logs-for-intrusion — 100% identical, 0 lines differ
- analyzing-linux-audit-logs-for-intrusion — 100% identical, 0 lines differ
- analyzing-linux-audit-logs-for-intrusion — 92% identical, 34 lines differ
- analyzing-linux-audit-logs-for-intrusion — 92% identical, 34 lines differ
- analyzing-linux-audit-logs-for-intrusion — 92% identical, 15 lines differ
- analyzing-linux-audit-logs-for-intrusion — 92% identical, 34 lines differ
How it starts
The opening of the file, as written. The whole thing — 276 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Analyzing Linux Audit Logs for Intrusion
When to Use
- Investigating suspected unauthorized access or privilege escalation on Linux hosts
- Hunting for evidence of exploitation, backdoor installation, or persistence mechanisms
- Auditing compliance with security baselines (CIS, STIG, PCI-DSS) that require system call monitoring
- Reconstructing a timeline of attacker actions during incident response
- Detecting file tampering on critical system files such as
/etc/passwd,/etc/shadow, or SSH keys
Do not use for network-level intrusion detection; use Suricata or Zeek for network traffic analysis. Auditd operates at the kernel level on individual hosts.
Prerequisites
- Linux system with
auditdpackage installed and the audit daemon running (systemctl status auditd) - Root or sudo access to configure audit rules and query logs
- Audit rules deployed via
/etc/audit/rules.d/*.rulesor loaded withauditctl - Recommended: Neo23x0/auditd ruleset from GitHub for comprehensive baseline coverage
- Familiarity with Linux syscalls (
execve,open,connect,ptrace, etc.) - Log storage with sufficient retention (default location:
/var/log/audit/audit.log)
Workflow
Step 1: Verify Audit Daemon Status and Configuration
Confirm the audit system is running and check the current rule set:
# Check auditd service status
systemctl status auditd
# Show current audit rules loaded in the kernel
auditctl -l
# Show audit daemon configuration
cat /etc/audit/auditd.conf | grep -E "log_file|max_log_file|num_logs|space_left_action"
# Check if the audit backlog is being exceeded (dropped events)
auditctl -s
If the backlog limit is being reached, increase it:
auditctl -b 8192
Step 2: Deploy Intrusion-Focused Audit Rules
Add rules that target common intrusion indicators. Place these in /etc/audit/rules.d/intrusion.rules:
# Monitor credential files for unauthorized reads or modifications
-w /etc/passwd -p wa -k credential_access
-w /etc/shadow -p rwa -k credential_access
-w /etc/gshadow -p rwa -k credential_access
-w /etc/sudoers -p wa -k privilege_escalation
-w /etc/sudoers.d/ -p wa -k privilege_escalation
# Monitor SSH configuration and authorized keys
-w /etc/ssh/sshd_config -p wa -k sshd_config_change
-w /root/.ssh/authorized_keys -p wa -k ssh_key_tampering
# Monitor user and group management commands
-w /usr/sbin/useradd -p x -k user_management
-w /usr/sbin/usermod -p x -k user_management
-w /usr/sbin/groupadd -p x -k user_management
# Detect process injection via ptrace
-a always,exit -F arch=b64 -S ptrace -F a0=0x4 -k process_injection
-a always,exit -F arch=b64 -S ptrace -F a0=0x5 -k process_injection
-a always,exit -F arch=b64 -S ptrace -F a0=0x6 -k process_injection
# Monitor execution of programs from unusual directories
-a always,exit -F arch=b64 -S execve -F exe=/tmp -k exec_from_tmp
-a always,exit -F arch=b64 -S execve -F exe=/dev/shm -k exec_from_shm
# Detect kernel module loading (rootkit installation)
-a always,exit -F arch=b64 -S init_module -S finit_module -k kernel_module_load
-a always,exit -F arch=b64 -S delete_module -k kernel_module_remove
-w /sbin/insmod -p x -k kernel_module_tool
-w /sbin/modprobe -p x -k kernel_module_tool
# Monitor network socket creation for reverse shells
-a always,exit -F arch=b64 -S socket -F a0=2 -k network_socket_created
-a always,exit -F arch=b64 -S connect -F a0=2 -k network_connection
# Detect cron job modifications (persistence)
-w /etc/crontab -p wa -k cron_persistence
-w /etc/cron.d/ -p wa -k cron_persistence
-w /var/spool/cron/ -p wa -k cron_persistence
# Monitor log deletion or tampering
-w /var/log/ -p wa -k log_tampering
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 12d ago First seen · 276 lines · 93 tokens per session scan B 36728ade3067
analyzing-linux-audit-logs-for-intrusion is a skill published in the GitHub repository mukul975/Anthropic-Cybersecurity-Skills (32,631 stars, last pushed 12d ago), licensed Apache-2.0. It adds 93 tokens to every session and 2,656 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it B with 2 findings (asks for root, reaches for credential files). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other skills, from other repositories
analyzing-linux-audit-logs-for-intrusion
Uses the Linux Audit framework (auditd) with ausearch and aureport utilities to detect intrusion attempts, unauthorized access, privilege escalation, and suspicious system activity. Covers audit rule configuration, log querying, timeline reconstruction, and integration with SIEM platforms. Activates for requests…
analyzing-linux-audit-logs-for-intrusion
Uses the Linux Audit framework (auditd) with ausearch and aureport utilities to detect intrusion attempts, unauthorized access, privilege escalation, and suspicious system activity. Covers audit rule configuration, log querying, timeline reconstruction, and integration with SIEM platforms. Activates for requests…
analyzing-linux-audit-logs-for-intrusion
Uses the Linux Audit framework (auditd) with ausearch and aureport utilities to detect intrusion attempts, unauthorized access, privilege escalation, and suspicious system activity. Covers audit rule configuration, log querying, timeline reconstruction, and integration with SIEM platforms. Activates for requests…
analyzing-linux-audit-logs-for-intrusion
Uses the Linux Audit framework (auditd) with ausearch and aureport utilities to detect intrusion attempts, unauthorized access, privilege escalation, and suspicious system activity. Covers audit rule configuration, log querying, timeline reconstruction, and integration with SIEM platforms. Activates for requests…
analyzing-linux-audit-logs-for-intrusion
Uses the Linux Audit framework (auditd) with ausearch and aureport utilities to detect intrusion attempts, unauthorized access, privilege escalation, and suspicious system activity. Covers audit rule configuration, log querying, timeline reconstruction, and integration with SIEM platforms. Activates for requests…
analyzing-linux-audit-logs-for-intrusion
Uses the Linux Audit framework (auditd) with ausearch and aureport utilities to detect intrusion attempts, unauthorized access, privilege escalation, and suspicious system activity. Covers audit rule configuration, log querying, timeline reconstruction, and integration with SIEM platforms. Activates for requests…