Add flaw 3: SQL injection

README.md

@@ -7,8 +7,6 @@ The point is to demonstrate common cyber security problems and their fixes.
 
 ## Description of vulnerabilities
 
-> **_NOTE:_** More detailed description of problems coming soon.
-
 I am using the 2021 OWASP Top Ten list.
 
 LINK: https://github.com/VSinerva/csb-project-1
@@ -46,7 +44,16 @@ If users already exist with weakly hashed passwords, a more complicated migratio
 FLAW 3:
 > ADD EXACT SOURCE LINK
 
-SQL Injection (Unsanitized SQL query for search)
+(Injection) The application has a classic SQL injection vunlerability in its search function.
+This is cause by taking the user input (search text) and placing it directly in the SQL query with a Python f-string.
+As an example, the "Search text" shown below will give any user a full listing of all usernames and their hashed passwords.
+`' AND 0=1 UNION SELECT date_joined, username || ":" || password as user, id FROM auth_user; --`
+Especially with flaws 2 and 4 present, this will quickly lead to a lot of compromised accounts.
+
+The fix to this issue is to properly escape/sanitize the user input e.g. by escaping control characters.
+This is difficult to do perfectly, so best practice is to use a well-known library or something similar for this.
+Luckily, Django has existing functionality for doing what we wanted to do, which will fix this issue.
+The commented out code implements this fixed version.
 
 
 FLAW 4:

notes/views.py

@@ -5,7 +5,6 @@ from django.contrib.auth.validators import UnicodeUsernameValidator
 from django.contrib.auth import authenticate, login, logout
 from django.contrib.auth.password_validation import validate_password
 from django.shortcuts import render, redirect
-from django.views.decorators.csrf import csrf_exempt
 from django.db import connection
 from django.core.exceptions import ValidationError
 
@@ -52,9 +51,16 @@ def search(request):
         user = request.user
         keyword = request.GET.get('keyword')
 
-        notes = Note.objects.filter(owner=user, body__icontains=keyword)
+# FLAW 3:
-        notes_list = [ { 'time' : note.time, 'body' : note.body, 'id' : note.id } for note in notes ]
+# Using the commented out version of the code uses Django's built in methods
-        notes_list.sort(key=lambda note: note['time'])
+# This makes sure the inputs are properly sanitized
+#        notes = Note.objects.filter(owner=user, body__icontains=keyword)
+#        notes_list = [ { 'time' : note.time, 'body' : note.body, 'id' : note.id } for note in notes ]
+#        notes_list.sort(key=lambda note: note['time'])
+        query = f"SELECT time, body, id FROM notes_note WHERE body LIKE '%{keyword}%' ORDER BY time;"
+        with connection.cursor() as cursor:
+            notes = cursor.execute(query).fetchall()
+        notes_list = [ { 'time' : note[0], 'body' : note[1], 'id' : note[2] } for note in notes ]
 
         return render(request, 'search.html', { 'notes' : notes_list, 'keyword' : keyword})