DC analyzing-persistence-mechanisms-in-linux
Scan Linux systems for persistence mechanisms including crontab/systemd entries, LD_PRELOAD injection, shell profile modifications (.bashrc, .profile), and SSH authorized_keys backdoors, then correlate findings with auditd logs into an installation timeline. Use during incident response or threat hunting to detect or confirm how an adversary maintained access to a compromised Linux host.
Scan Linux systems for persistence mechanisms including crontab/systemd entries, LDPRELOAD injection, shell profile modifications (.bashrc, .profile), and SSH…
As a process C 54/100 · Has gaps — weak spots: result and completion, when it triggers, failures and branches
What is at stake
Medium-severity findings: the skill is probably honest, but read what alarmed the scanner.
Below is the worst case for this category. The finding here is medium: the guard saw a sign, not a proof.
The skill contains commands that delete files, rewrite disks or execute code fetched from the network. The agent may run them without asking if it believes the instructions require it.
Replace destructive commands with safe equivalents that ask for confirmation, scope them to one folder, and stop piping curl into a shell: pin a version and a checksum.
How to improve
- Your own cases (evals/evals.json, 4–6 real requests with expected answers): the full check would then run those instead of a model-drafted suite.
- A spec.yaml with trigger phrases and assertions — a behaviour contract for CI; `skilltest init` writes a template.
Guard findings · 10
✓ No critical or high findings
Medium and low: 10
-
medium Dangerous commands
cmd-persistencereferences/api-reference.md:13Persistence mechanism (cron / launchd / scheduled task / autorun registry) (documentation of a security skill)ls -la /etc/cron.d/ /etc/cron.daily/ /etc/cron.hourly/ /etc/cron.weekly/ /etc/cron.monthly/
security skill -
medium Dangerous commands
cmd-persistencereferences/api-reference.md:14Persistence mechanism (cron / launchd / scheduled task / autorun registry) (documentation of a security skill)cat /etc/crontab
security skill -
medium Dangerous commands
cmd-persistencereferences/api-reference.md:60Persistence mechanism (cron / launchd / scheduled task / autorun registry) (documentation of a security skill)-w /etc/crontab -p wa -k cron_modification
security skill -
medium Dangerous commands
cmd-persistencereferences/api-reference.md:61Persistence mechanism (cron / launchd / scheduled task / autorun registry) (documentation of a security skill)-w /etc/cron.d/ -p wa -k cron_modification
security skill -
medium Dangerous commands
cmd-persistencescripts/agent.py:14Persistence mechanism (cron / launchd / scheduled task / autorun registry) (string literal in code, not executed)"/etc/crontab", "/etc/cron.d/", "/etc/cron.daily/", "/etc/cron.hourly/",
code literal -
medium Dangerous commands
cmd-persistencescripts/agent.py:15Persistence mechanism (cron / launchd / scheduled task / autorun registry) (string literal in code, not executed)"/etc/cron.weekly/", "/etc/cron.monthly/", "/var/spool/cron/crontabs/",
code literal -
low Dangerous commands
cmd-cron-mentionreferences/api-reference.md:7Mentions editing / listing crontab (documentation of a security skill)crontab -l
security skill -
low Dangerous commands
cmd-cron-mentionreferences/api-reference.md:10Mentions editing / listing crontab (documentation of a security skill)crontab -l -u username
security skill -
low Dangerous commands
cmd-cron-mentionscripts/agent.py:46Mentions editing / listing crontab (string literal in code, not executed)["bash", "-c", "for u in $(cut -d: -f1 /etc/passwd); do crontab -l -u $u 2>/dev/null && echo \"__USER:$u\"; done"],
code literal
A further 1 matches are quotations in this security skill's documentation and are not counted as findings.
Files scanned: 4. Evidence is masked. Grey chips explain why severity was lowered.
Against the Agent Skills spec
- note
frontmatter-keyunknown frontmatter key "domain" - note
frontmatter-keyunknown frontmatter key "subdomain" - note
frontmatter-keyunknown frontmatter key "mitre_attack" - note
frontmatter-keyunknown frontmatter key "d3fend_techniques" - note
frontmatter-keyunknown frontmatter key "nist_csf"
Process rating: all ten parameters 54/100
- 0Result and completion. Does not say what the result is
- 0Failures and branches. Linear process with no failure handling
- 0Progress reporting. Says nothing while it works
- 20When it triggers. No condition that starts the skill
- 60Tools and files. Uses tools (bash, python) that frontmatter does not declare
- 70Inputs and preconditions. Inputs and preconditions are listed
- 100Steps. 19 steps
- 100Consistency. Name and required fields are in place
- 100Execution cost. Instruction body is 565 tokens
- 100Running it twice. No mutating operations
Everything here is measured from the skill text rather than judged by a model, so the numbers are checkable. A parameter weighs more when it is a more common reason for the process to stall.
Quality signals
- +5Description has no quoted example phrases that should trigger the skill
- +4Description does not say when NOT to use the skill (false activations)
- +3Output format is not stated: the model decides each time
- +4No input/output examples
- -41 reference files, but SKILL.md never points to them: the model will not open them
- -31 of 1 scripts are never mentioned in SKILL.md
- +2Single-language instructions
- +3Description length 390: enough signal without eating the budget
- +4Structure: 6 headings
- +3Step-by-step instructions: 19 items
- +1License stated
Quality base 70; lint remarks subtract, signals add up to 100. Result: 71.