Myco— agent skill

Myco — independently scanned and version-tracked by SaferSkills.

by Battam1111·Agent Skill·github.com/Battam1111/Myco

Is Myco safe to install?

SaferSkills independently audited Myco (Agent Skill) and scored it 45/100 (orange). The audit ran 55 deterministic rules across Security, Supply Chain, Maintenance, Transparency, and Community; it found 7 high-severity and 0 lower-severity findings. The full rule-by-rule trace and per-finding evidence are below. Free, methodology-open.

Score
45/100
●●●●●○○○○○
↑ +0 since first scan (45 → 45)Re-scan~30s
Latest scan
ScannedJun 23, 2026 · 33d ago
Scans run1 over 90 days
Detectors55 checks · 5 categories
Findings0 warnings · 7 high
EngineSaferSkills 2b638c6
View methodology →
SaferSkills installs
This week0
This month0
All time0
CategoryWeightCategory scoreContribution
Securityprompt, exec, net, exfil, eval
35%
0
0.0 pts
Supply chainhash, typosquat, maintainer, lockfile
20%
100
20.0 pts
Maintenancestaleness, pinning, CI
15%
100
15.0 pts
TransparencySKILL.md, perms, README
15%
100
15.0 pts
Communityinstalls, verify, response
15%
100
15.0 pts

Findings & checks · 7 flagged

Securityscore 0 · 7 findings
HIGHLong base64-encoded blob hidden in the skill documentationSS-SKILL-INJECT-B64-PAYLOAD-01 · Prompt injection · test_vectors/crypto_v1.json×7
HIGHonce decoded by the agent, an encoded payload has the same impact class as plain-text injection.
Why it matters

A base64 string of 128+ characters appears in a documentation file. Encoded prompt injection hides the hostile instruction in base64 — invisible to keyword filters — and relies on the agent's ability to decode it at runtime. There is no normal authoring reason to embed a multi-hundred-byte base64 blob in skill docs.

The exact value spotted
excerpttest_vectors/crypto_v1.json· json
85"name": "hmac_long_key",
86"_description": "100-byte key (longer than SHA-256 block size of 64 bytes; HMAC must interna
… (48 chars elided on L86)
87"key_hex": "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
… (100 chars elided on L87)
88"msg_hex": "01020304",
89"output_hex": "8d071581b5d75b4071446c14a7e77923cd8996f634396d317db8a7f6792e72ed"
Occurrences
7 occurrences · first at L87, also L111, L116 +4 more
Show all 7 locations
Line
File
L87
test_vectors/crypto_v1.json
L111
test_vectors/crypto_v1.json
L116
test_vectors/crypto_v1.json
L121
test_vectors/crypto_v1.json
L127
test_vectors/crypto_v1.json
L135
test_vectors/crypto_v1.json
L142
test_vectors/crypto_v1.json
How to fix
Remove the encoded blob, or decode it and review what it actually contains.
  1. Decode the base64 string and confirm it is not an instruction directed at the agent.
  2. Move any legitimate binary or signature data into a dedicated file (*.sig, SIGNATURES) outside the documentation.
Framework references
OWASPLLM01ATLASAML.T0051
Trace & refs
ruleSS-SKILL-INJECT-B64-PAYLOAD-01sha256aaebc35c4c4e2cc7rubric 365aacaView on GitHub
Supply chainscore 100 · 0 findings
All supply chain checks passedNo findings in this category for the latest scan.pass
Maintenancescore 100 · 0 findings
All maintenance checks passedNo findings in this category for the latest scan.pass
Transparencyscore 100 · 0 findings
All transparency checks passedNo findings in this category for the latest scan.pass
Communityscore 100 · 0 findings
All community checks passedNo findings in this category for the latest scan.pass
Vendor response · right of reply
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