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pyLoad allows upload to arbitrary folder lead to RCE

Critical severity GitHub Reviewed Published Apr 24, 2024 in pyload/pyload • Updated Apr 26, 2024

Package

pip pyload-ng (pip)

Affected versions

<= 0.5.0

Patched versions

None

Description

Summary

An authenticated user can change the download folder and upload a crafted template to the specified folder lead to remote code execution

Details

example version: 0.5
file:src/pyload/webui/app/blueprints/app_blueprint.py

@bp.route("/render/<path:filename>", endpoint="render")
def render(filename):
    mimetype = mimetypes.guess_type(filename)[0] or "text/html"
    data = render_template(filename)
    return flask.Response(data, mimetype=mimetype)

So, if we can control file in the path "pyload/webui/app/templates" in latest version and path in "module/web/media/js"(the difference is the older version0.4.20 only renders file with extension name ".js"), the render_template func will works like SSTI(server-side template injection) when render the evil file we control.

in /settings page and the choose option general/general, where we can change the download folder.
image

Also, we can find the pyLoad install folder in /info page
image
So, we can change the value of Download folder to the template path. Then through /json/add_package we can upload a crafted template file to RCE.

@bp.route("/json/add_package", methods=["POST"], endpoint="add_package")
# @apiver_check
@login_required("ADD")
def add_package():
    api = flask.current_app.config["PYLOAD_API"]

    package_name = flask.request.form.get("add_name", "New Package").strip()
    queue = int(flask.request.form["add_dest"])
    links = [l.strip() for l in flask.request.form["add_links"].splitlines()]
    pw = flask.request.form.get("add_password", "").strip("\n\r")

    try:
        file = flask.request.files["add_file"]

        if file.filename:
            if not package_name or package_name == "New Package":
                package_name = file.filename

            file_path = os.path.join(
                api.get_config_value("general", "storage_folder"), "tmp_" + file.filename
            )
            file.save(file_path)
            links.insert(0, file_path)

    except Exception:
        pass

    urls = [url for url in links if url.strip()]
    pack = api.add_package(package_name, urls, queue)
    if pw:
        data = {"password": pw}
        api.set_package_data(pack, data)

    return jsonify(True)

PoC

First login into the admin page, then visit the info page to get the path of pyload installation folder.
Second, change the download folder to PYLOAD_INSTALL_DIR/ webui/app/templates/
Third, upload crafted template file through /json/add_package through parameter add_file
the content of crafted template file and its filename is "341.html":

{{x.__init__.__globals__['__builtins__']['eval']("__import__('os').popen('whoami').read()")}}

image
Last, visit http://TARGET/render/tmp_341.html to trigger the RCE
image
image

Impact

It is a RCE vulnerability and I think it affects all versions. In earlier version 0.4.20, the trigger difference is the pyload installation folder path difference and the upload file must with extension ".js" .
The render js code in version 0.4.20:

@route("/media/js/<path:re:.+\.js>")
def js_dynamic(path):
    response.headers['Expires'] = time.strftime("%a, %d %b %Y %H:%M:%S GMT",
                                                time.gmtime(time.time() + 60 * 60 * 24 * 2))
    response.headers['Cache-control'] = "public"
    response.headers['Content-Type'] = "text/javascript; charset=UTF-8"

    try:
        # static files are not rendered
        if "static" not in path and "mootools" not in path:
            t = env.get_template("js/%s" % path)
            return t.render()
        else:
            return static_file(path, root=join(PROJECT_DIR, "media", "js"))
    except:
        return HTTPError(404, "Not Found")

References

@GammaC0de GammaC0de published to pyload/pyload Apr 24, 2024
Published to the GitHub Advisory Database Apr 24, 2024
Reviewed Apr 24, 2024
Published by the National Vulnerability Database Apr 26, 2024
Last updated Apr 26, 2024

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

EPSS score

0.043%
(10th percentile)

Weaknesses

CVE ID

CVE-2024-32880

GHSA ID

GHSA-3f7w-p8vr-4v5f

Source code

Credits

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