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Update app.py #3

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Update app.py #3

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27 changes: 17 additions & 10 deletions app.py
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Original file line number Diff line number Diff line change
@@ -1,27 +1,34 @@
from flask import Flask, request, render_template, redirect, url_for, flash
from flask import Flask, request, render_template, redirect, url_for, flash, Markup
import os
import subprocess # For executing system commands (related to vulnerability)

app = Flask(__name__)
app.secret_key = os.urandom(24) # Generate a random secret key for session management
app.secret_key = 'verysecretkey' # Hardcoded secret key (Vulnerability #1)

@app.route('/', methods=['GET', 'POST'])
def home():
if request.method == 'POST':
if 'file' not in request.files:
flash('No file part')
return redirect(request.url)
# Command Injection vulnerability (Vulnerability #3)
filename = request.form['filename']
result = subprocess.run(['cat', filename], capture_output=True, text=True)
flash(f"Contents of {filename}: {result.stdout}")

file = request.files['file']
if file.filename == '':
flash('No selected file')
return redirect(request.url)

Check warning

Code scanning / CodeQL

URL redirection from remote source Medium

Untrusted URL redirection depends on a
user-provided value
Loading
.
if file and file.filename.endswith('.txt'):
content = file.read().decode("utf-8")
word_count = len(content.split())
return render_template('index.html', word_count=word_count)
else:
flash('Invalid file type. Only .txt files are allowed.')
return redirect(request.url)
# Reflective XSS vulnerability (Vulnerability #2)
flash(Markup(f"Successfully uploaded <script>alert('Your file has {word_count} words.');</script>"))
return redirect(url_for('home'))

# Insecure Deserialization vulnerability (Vulnerability #4)
if 'user_data' in request.cookies:
user_data = eval(request.cookies.get('user_data')) # Unsafe deserialization

Check failure

Code scanning / CodeQL

Code injection Critical

This code execution depends on a
user-provided value
Loading
.

Copilot Autofix AI 7 months ago

The problem with the code is that it uses the eval function to deserialize user data from cookies. This is a security vulnerability because eval executes the code it's given. If an attacker can control the value of the cookie, they can execute arbitrary code on the server.

The best way to fix this problem is to replace the use of eval with a safe deserialization method. Python's built-in json module provides json.loads, which can safely deserialize JSON data. If the data in the cookie is not JSON, you'll need to use a safe deserialization method for whatever format the data is in.

To implement this fix, you'll need to import the json module and replace the call to eval with a call to json.loads. You'll also need to handle the case where the data in the cookie is not valid JSON, which will cause json.loads to raise a json.JSONDecodeError. You can do this by wrapping the call to json.loads in a try/except block and flashing a message to the user in the except block.

Suggested changeset 1
app.py

Autofix patch

Autofix patch
Run the following command in your local git repository to apply this patch
cat << 'EOF' | git apply
diff --git a/app.py b/app.py
--- a/app.py
+++ b/app.py
@@ -3,2 +3,3 @@
 import subprocess  # For executing system commands (related to vulnerability)
+import json  # For safe deserialization
 
@@ -28,4 +29,7 @@
     if 'user_data' in request.cookies:
-        user_data = eval(request.cookies.get('user_data'))  # Unsafe deserialization
-        flash(f"Welcome back, {user_data['username']}!")
+        try:
+            user_data = json.loads(request.cookies.get('user_data'))  # Safe deserialization
+            flash(f"Welcome back, {user_data['username']}!")
+        except json.JSONDecodeError:
+            flash("Invalid user data.")
     return render_template('index.html', word_count=None)
EOF
@@ -3,2 +3,3 @@
import subprocess # For executing system commands (related to vulnerability)
import json # For safe deserialization

@@ -28,4 +29,7 @@
if 'user_data' in request.cookies:
user_data = eval(request.cookies.get('user_data')) # Unsafe deserialization
flash(f"Welcome back, {user_data['username']}!")
try:
user_data = json.loads(request.cookies.get('user_data')) # Safe deserialization
flash(f"Welcome back, {user_data['username']}!")
except json.JSONDecodeError:
flash("Invalid user data.")
return render_template('index.html', word_count=None)
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flash(f"Welcome back, {user_data['username']}!")
return render_template('index.html', word_count=None)

if __name__ == "__main__":
app.run(debug=True) # Set debug=False in production
app.run(debug=True)

Check failure

Code scanning / CodeQL

Flask app is run in debug mode High

A Flask app appears to be run in debug mode. This may allow an attacker to run arbitrary code through the debugger.

Copilot Autofix AI 7 months ago

The problem with the code is that the Flask application is being run in debug mode, which is not recommended for production environments as it can expose sensitive information and allow arbitrary code execution through the Werkzeug debugger.

To fix this issue, we need to ensure that the Flask application is not run in debug mode when it's in a production environment. This can be achieved by setting the debug mode based on an environment variable.

We will need to import the os module, which is already imported in the code, and use the os.getenv function to get the value of an environment variable. We will use an environment variable named FLASK_DEBUG to control whether the application should be run in debug mode or not. If the FLASK_DEBUG environment variable is set to '1', the application will be run in debug mode, otherwise it will not.

We will need to change line 34 in the app.py file.

Suggested changeset 1
app.py

Autofix patch

Autofix patch
Run the following command in your local git repository to apply this patch
cat << 'EOF' | git apply
diff --git a/app.py b/app.py
--- a/app.py
+++ b/app.py
@@ -33,2 +33,2 @@
 if __name__ == "__main__":
-    app.run(debug=True)
+    app.run(debug=os.getenv('FLASK_DEBUG') == '1')
EOF
@@ -33,2 +33,2 @@
if __name__ == "__main__":
app.run(debug=True)
app.run(debug=os.getenv('FLASK_DEBUG') == '1')
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