CVE-2023-37481 (Python, published 2023-07-18T19:15Z)
Description: value: Fides is an open-source privacy engineering platform for managing data privacy requests and privacy regulations. The Fides webserver is vulnerable to a type of Denial of Service (DoS) attack. Attackers can exploit this vulnerability to upload zip files containing malicious SVG bombs (similar to a billion laughs attack), causing resource exhaustion in Admin UI browser tabs and creating a persistent denial of service of the 'new connector' page (`datastore-connection/new`). This vulnerability affects Fides versions `2.11.0` through `2.15.1`. Exploitation is limited to users with elevated privileges with the `CONNECTOR_TEMPLATE_REGISTER` scope, which includes root users and users with the owner role. The vulnerability has been patched in Fides version `2.16.0`. Users are advised to upgrade to this version or later to secure their systems against this threat. There is no known workaround to remediate this vulnerability without upgrading.
Severity: nan (CVSS v3 base score: 4.9)
Weakness: CWE-400 \u2014 Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.
Repository: https://github.com/ethyca/fides
Files changed:
requirements.txt
src/fides/api/service/connectors/saas/connector_registry_service.py
src/fides/api/util/unsafe_file_util.py
tests/ops/util/test_unsafe_file_util.py
Commit message: Merge pull request from GHSA-3rw2-wfc8-wmj5

* Adding checks for malicious SVGs

* Fixing merge conflicts

---------

Co-authored-by: Dave Quinlan <83430497+daveqnet@users.noreply.github.com>

Vulnerable code:
from fides.api.util.unsafe_file_util import verify_zip
from fides.api.util.unsafe_file_util import verify_zip

Fixed code:
defusedxml==0.7.1
from fides.api.util.unsafe_file_util import verify_svg, verify_zip
                    verify_svg(file_contents)
from defusedxml.ElementTree import fromstring

from fides.api.common_exceptions import ValidationError

def verify_svg(contents: str) -> None:
    """
    Verifies the provided SVG content.

    This function checks the given SVG content string for potential issues and throws an exception if any are found.
    It first attempts to parse the SVG content using 'defusedxml.fromstring'. If the parsing is unsuccessful, this
    will raise an exception, indicating that the SVG content may contain unsafe XML.

    :param contents: The SVG content as a string.
    :raises ValidationError: If the SVG content contains unsafe XML or 'use xlink'
    """
    try:
        fromstring(contents)
    except Exception:
        raise ValidationError("SVG file contains unsafe XML.")

    if "use xlink" in contents:
        raise ValidationError("SVG files with xlink references are not allowed.")


from fides.api.common_exceptions import ValidationError
from fides.api.util.unsafe_file_util import verify_svg, verify_zip
class TestVerifySvg:
    def test_verify_svg(self):
        verify_svg(
            """<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
                <circle cx="50" cy="50" r="40"/>
            </svg>
            """
        )

    def test_verify_svg_no_laughing_allowed(self):
        """Test "billion laughs attack" is prevented"""
        with pytest.raises(ValidationError) as exc:
            verify_svg(
                """<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
                <!DOCTYPE svg [
                <!ENTITY lol "lol">
                <!ELEMENT lolz (#PCDATA)>
                <!ENTITY lol1 "&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;">
                <!ENTITY lol2 "&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;&lol1;">
                <!ENTITY lol3 "&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;">
                <!ENTITY lol4 "&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;">
                <!ENTITY lol5 "&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;">
                <!ENTITY lol6 "&lol5;&lol5;&lol5;&lol5;&lol5;&lol5;&lol5;&lol5;&lol5;&lol5;">
                <!ENTITY lol7 "&lol6;&lol6;&lol6;&lol6;&lol6;&lol6;&lol6;&lol6;&lol6;&lol6;">
                <!ENTITY lol8 "&lol7;&lol7;&lol7;&lol7;&lol7;&lol7;&lol7;&lol7;&lol7;&lol7;">
                <!ENTITY lol9 "&lol8;&lol8;&lol8;&lol8;&lol8;&lol8;&lol8;&lol8;&lol8;&lol8;">
                ]>
                <svg>
                    <lolz>&lol9;</lolz>
                </svg>
                """
            )
        assert "SVG file contains unsafe XML." in str(exc.value)

    def test_verify_svg_with_xlink(self):
        with pytest.raises(ValidationError) as exc:
            verify_svg(
                """<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 100 100">
                    <circle id="circle" cx="50" cy="50" r="40"/>
                    <use xlink:href="#circle"/>
                </svg>
                """
            )
        assert "SVG files with xlink references are not allowed." in str(exc.value)