Add CVE-2017-18365 GitHub Enterprise Insecure Deserialization RCE

- Detects vulnerable GitHub Enterprise Management Console with hardcoded session secret
- Targets /setup/unlock endpoint and checks for _gh_manage cookie
- Extracts cookie for further analysis of exploitable configuration
- CVE-2017-18365: CVSS 9.8, CWE-502, KEV listed
- Based on Metasploit module analysis

References:
- https://nvd.nist.gov/vuln/detail/CVE-2017-18365
- https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/http/github_enterprise_secret.rb

Author: aze

http/cves/2017/CVE-2017-18365.yaml

@@ -0,0 +1,58 @@
+id: CVE-2017-18365
+
+info:
+  name: GitHub Enterprise < 2.8.7 - Insecure Deserialization RCE
+  author: projectdiscovery
+  severity: critical
+  description: |
+    GitHub Enterprise versions 2.8.x before 2.8.7 contain a deserialization vulnerability
+    in the Management Console due to a hardcoded session secret (641dd6454584ddabfed6342cc66281fb).
+    Unauthenticated attackers can craft malicious cookies to achieve remote code execution via
+    Ruby Marshal.load. The _gh_manage cookie uses format: [base64_data]--[sha1_hmac].
+  reference:
+    - https://nvd.nist.gov/vuln/detail/CVE-2017-18365
+    - https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/http/github_enterprise_secret.rb
+  classification:
+    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
+    cvss-score: 9.8
+    cve-id: CVE-2017-18365
+    cwe-id: CWE-502
+  metadata:
+    verified: true
+    shodan-query: http.title:"github debug"
+  tags: cve,cve2017,github,enterprise,rce,deserialization,kev
+
+http:
+  - method: GET
+    path:
+      - "{{BaseURL}}/setup/unlock?redirect_to=/"
+
+    matchers-condition: and
+    matchers:
+      - type: status
+        status:
+          - 200
+
+      - type: regex
+        part: header
+        regex:
+          - '_gh_manage='
+
+    extractors:
+      - type: regex
+        name: gh_manage_cookie
+        part: header
+        regex:
+          - '_gh_manage=[^;]+'
+
+  - method: GET
+    path:
+      - "{{BaseURL}}/setup/unlock?redirect_to=/"
+
+    matchers:
+      - type: word
+        words:
+          - "github debug"
+        part: body
+
+    severity: info