refactor old-12 (CSRF-2)

pwncollege · Sep 2, 2024 · 85ba023 · 85ba023
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diff --git a/web-security/level-12/.config b/web-security/level-12/.config
diff --git a/web-security/level-12/DESCRIPTION.md b/web-security/level-12/DESCRIPTION.md
@@ -0,0 +1,9 @@
+Recall that requests that originate from JavaScript run into the Same-Origin Policy, which slightly complicated our CSRF in the previous level.
+You figured out how to make a `GET` request without JavaScript.
+Can you do the same for `POST`?
+
+Recall that a typical `POST` request is a result of either a JavaScript-invoked request (no good for SOP) or an HTML form submission.
+You'll need to do the latter.
+Of course, the `/challenge/victim` won't click the `Submit` button for you --- you'll have to figure out how to do that yourself (HINT: JavaScript can click that button; the request will still count as originating from the form!).
+
+Go `POST`-CSRF to the flag!
diff --git a/web-security/level-12/run b/web-security/level-12/run
diff --git a/web-security/level-12/server b/web-security/level-12/server
@@ -0,0 +1,104 @@
+#!/opt/pwn.college/python
+
+import tempfile
+import sqlite3
+import flask
+import os
+
+app = flask.Flask(__name__)
+
+class TemporaryDB:
+    def __init__(self):
+        self.db_file = tempfile.NamedTemporaryFile("x", suffix=".db")
+
+    def execute(self, sql, parameters=()):
+        connection = sqlite3.connect(self.db_file.name)
+        connection.row_factory = sqlite3.Row
+        cursor = connection.cursor()
+        result = cursor.execute(sql, parameters)
+        connection.commit()
+        return result
+
+flag = open("/flag").read().strip() if os.getuid() == 0 else "pwn.college{fake_flag}"
+
+db = TemporaryDB()
+# https://www.sqlite.org/lang_createtable.html
+db.execute("""CREATE TABLE posts AS SELECT ? AS content, "admin" AS author, FALSE AS published""", [flag])
+db.execute("""CREATE TABLE users AS SELECT "admin" AS username, ? as password""", [flag])
+# https://www.sqlite.org/lang_insert.html
+db.execute("""INSERT INTO users SELECT "guest" as username, "password" as password""")
+db.execute("""INSERT INTO users SELECT "hacker" as username, "1337" as password""")
+
+@app.route("/login", methods=["POST"])
+def challenge_login():
+    username = flask.request.form.get("username")
+    password = flask.request.form.get("password")
+    if not username:
+        flask.abort(400, "Missing `username` form parameter")
+    if not password:
+        flask.abort(400, "Missing `password` form parameter")
+
+    # https://www.sqlite.org/lang_select.html
+    user = db.execute("SELECT * FROM users WHERE username = ? AND password = ?", (username, password)).fetchone()
+    if not user:
+        flask.abort(403, "Invalid username or password")
+
+    flask.session["username"] = username
+    return flask.redirect("/")
+
+@app.route("/draft", methods=["POST"])
+def challenge_draft():
+    if "username" not in flask.session:
+        flask.abort(403, "Log in first!")
+
+    content = flask.request.form.get("content", "")
+    # https://www.sqlite.org/lang_insert.html
+    db.execute(
+        "INSERT INTO posts (content, author, published) VALUES (?, ?, ?)",
+        (content, flask.session.get("username"), bool(flask.request.form.get("publish")))
+    )
+    return flask.redirect("/")
+
+@app.route("/publish", methods=["POST"])
+def challenge_publish():
+    if "username" not in flask.session:
+        flask.abort(403, "Log in first!")
+
+    # https://www.sqlite.org/lang_update.html
+    db.execute("UPDATE posts SET published = TRUE WHERE author = ?", [flask.session.get("username")])
+    return flask.redirect("/")
+
+@app.route("/", methods=["GET"])
+def challenge_get():
+    page = "<html><body>\nWelcome to pwnpost, now XSS-free (for admin, at least)!<hr>\n"
+    username = flask.session.get("username", None)
+    if username == "admin":
+        page += """<b>To prevent XSS, the admin does not view messages!</b>"""
+    elif username:
+        page += """
+            <form action=draft method=post>
+              Post:<textarea name=content>Write something!</textarea>
+              <input type=checkbox name=publish>Publish
+              <input type=submit value=Save>
+            </form><br><a href=publish>Publish your drafts!</a><hr>
+        """
+
+        for post in db.execute("SELECT * FROM posts").fetchall():
+            page += f"""<h2>Author: {post["author"]}</h2>"""
+            if post["published"]:
+                page += post["content"] + "<hr>\n"
+            else:
+                page += f"""(Draft post, showing first 12 characters):<br>{post["content"][:12]}<hr>"""
+    else:
+        page += """
+            <form action=login method=post>
+              Username:<input type=text name=username>
+              Password:<input type=text name=password>
+              <input type=submit name=submit value=Login>
+            </form><hr>
+        """
+
+    return page + "</body></html>"
+
+app.secret_key = os.urandom(8)
+app.run("challenge.localhost", 8080 if os.geteuid() else 80)
diff --git a/web-security/level-12/victim b/web-security/level-12/victim
@@ -0,0 +1,56 @@
+#!/opt/pwn.college/python
+
+import psutil
+import urllib
+import atexit
+import time
+import sys
+import os
+
+from selenium import webdriver
+from selenium.webdriver.firefox.options import Options as FirefoxOptions
+from selenium.webdriver.firefox.service import Service as FirefoxService
+from selenium.webdriver.common.by import By
+from selenium.webdriver.support.wait import WebDriverWait
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.common.exceptions import TimeoutException, WebDriverException
+
+os.setuid(os.geteuid())
+os.environ.clear()
+os.environ["PATH"] = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+
+options = FirefoxOptions()
+options.add_argument("--headless")
+service = FirefoxService(log_path="/dev/null")
+
+browser = webdriver.Firefox(service=service, options=options)
+atexit.register(browser.quit)
+
+open_ports = { s.laddr.port for s in psutil.net_connections(kind="inet") if s.status == 'LISTEN' }
+if 80 in open_ports:
+    print("Port 80 is open. Will connect to the service there.")
+    challenge_url = "http://challenge.localhost:80/"
+    flag = open("/flag").read().strip()
+elif 8080 in open_ports:
+    print("Port 8080 is open. Will connect to the service there. 8080 is the debug port, so you will earn a fake flag.")
+    challenge_url = "http://challenge.localhost:8080/"
+    flag = "pwn.college{fake_flag}"
+else:
+    print("Services don't seem to be running?")
+    sys.exit(1)
+
+print(f"Visiting {challenge_url}")
+browser.get(challenge_url)
+
+print("Logging in as admin...")
+browser.find_element(By.NAME, "username").send_keys("admin")
+browser.find_element(By.NAME, "password").send_keys(flag)
+browser.find_element(By.NAME, "submit").submit()
+time.sleep(3)
+print("Logged in!")
+
+print("Visiting the attacker's website (http://hacker.localhost:1337/)...")
+browser.get("http://hacker.localhost:1337/")
+time.sleep(3)
+
+print("Visited! Go check if the attack worked!")
diff --git a/web-security/module.yml b/web-security/module.yml
@@ -48,7 +48,6 @@ challenges:
   name: CSRF 1
 - id: level-12
   name: CSRF 2
-  description: Exploit a cross site request forgery vulnerability where the request must POST
 - id: level-13
   name: CSRF 3
   description: Exploit a cross site scripting vulnerability to exfiltrate user session data