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[critical] fix: [html_to_markdown] close SSRF holes in the URL safety check #848

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[critical] fix: [html_to_markdown] close SSRF holes in the URL safety check #848

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27 changes: 12 additions & 15 deletions misp_modules/modules/expansion/html_to_markdown.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@

import requests
import ipaddress
from urllib.parse import urlparse
from urllib.parse import urljoin, urlparse
from bs4 import BeautifulSoup
from markdownify import markdownify

Expand All @@ -27,14 +27,7 @@
}


BLOCKED_RANGES = [
ipaddress.ip_network("127.0.0.0/8"),
ipaddress.ip_network("10.0.0.0/8"),
ipaddress.ip_network("172.16.0.0/12"),
ipaddress.ip_network("192.168.0.0/16"),
ipaddress.ip_network("169.254.0.0/16"),
ipaddress.ip_network("::1/128"),
]
MAX_REDIRECTS = 5


def _normalize_ip_address(ip_str: str) -> ipaddress.IPv4Address | ipaddress.IPv6Address:
Expand All @@ -43,8 +36,7 @@ def _normalize_ip_address(ip_str: str) -> ipaddress.IPv4Address | ipaddress.IPv6


def _is_ip_blocked(ip_str: str) -> bool:
ip = _normalize_ip_address(ip_str)
return any(ip in net for net in BLOCKED_RANGES)
return not _normalize_ip_address(ip_str).is_global


def _hostname_resolves_to_blocked_ip(hostname: str) -> bool:
Expand All @@ -66,10 +58,15 @@ def is_safe_url(url: str) -> bool:


def fetchHTML(url):
if not is_safe_url(url):
raise ValueError(f"Blocked URL: {url}")
r = requests.get(url, timeout=10)
return r.text
for _ in range(MAX_REDIRECTS + 1):
if not is_safe_url(url):
raise ValueError(f"Blocked URL: {url}")
r = requests.get(url, timeout=10, allow_redirects=False)
if r.is_redirect and r.headers.get("location"):
url = urljoin(url, r.headers["location"])
continue
return r.text
raise ValueError(f"Too many redirects: {url}")


def stripUselessTags(html):
Expand Down