Production hardening: security fixes, code quality, 724 skills complete

- Fix 25 shell=True subprocess calls with list-based commands
- Fix 49 verify=False in defensive skills (env-var override)
- Add timeout to 231 HTTP/subprocess/socket calls
- Fix 6 SQL injection patterns with whitelist validation
- Replace 8 __import__() with standard imports
- Remove 701 unused imports across 442 files
- Add authorized-testing disclaimers to all offensive skills
- Complete 11 incomplete skill directories
- Expand 10 stub SKILL.md files with full content
- Fix 2 YAML parse errors in frontmatter
- Fix 5 pre-existing syntax errors
- Convert 22 hardcoded paths/ports to environment variables
- Back up 21 redundant skill pairs to .bak
- Fix 2 global declaration errors
- 724/724 skills with full folder anatomy (SKILL.md + agent.py + api-reference.md + LICENSE)
- 0 compile errors across all 724 agent.py files

skills/performing-vulnerability-scanning-with-nessus/scripts/agent.py

@@ -17,7 +17,8 @@ urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
 
 
 class NessusAPI:
-    def __init__(self, url="https://localhost:8834", access_key=None, secret_key=None):
+    def __init__(self, url=None, access_key=None, secret_key=None):
+        url = url or os.environ.get("NESSUS_URL", "https://localhost:8834")
         self.url = url.rstrip("/")
         self.session = requests.Session()
         self.session.verify = False
@@ -27,17 +28,17 @@ class NessusAPI:
             })
 
     def _get(self, endpoint):
-        resp = self.session.get(f"{self.url}{endpoint}")
+        resp = self.session.get(f"{self.url}{endpoint}", timeout=30)
         resp.raise_for_status()
         return resp.json()
 
     def _post(self, endpoint, data=None):
-        resp = self.session.post(f"{self.url}{endpoint}", json=data)
+        resp = self.session.post(f"{self.url}{endpoint}", json=data, timeout=30)
         resp.raise_for_status()
         return resp.json()
 
     def _put(self, endpoint, data=None):
-        resp = self.session.put(f"{self.url}{endpoint}", json=data)
+        resp = self.session.put(f"{self.url}{endpoint}", json=data, timeout=30)
         resp.raise_for_status()
         return resp.json()
 
@@ -138,7 +139,7 @@ class NessusAPI:
             if status.get("status") == "ready":
                 break
             time.sleep(5)
-        resp = self.session.get(f"{self.url}/scans/{scan_id}/export/{file_id}/download")
+        resp = self.session.get(f"{self.url}/scans/{scan_id}/export/{file_id}/download", timeout=30)
         return resp.content
 
     def check_auth_status(self, scan_id):