SQL injection protection via ORM in Django - Step-by-Step Execution

Concept Flow - SQL injection protection via ORM

User Input Received

↓

Input Passed to ORM Query

↓

ORM Escapes Input

↓

Safe SQL Query Generated

↓

Database Executes Query

↓

Results Returned Safely

User input goes into ORM queries, which automatically escape it to prevent harmful SQL code, then safely run the query and return results.

Execution Sample

Django

user_input = "1 OR 1=1"
result = User.objects.filter(username=user_input)
print(result.query)

This code tries to filter users by an unsafe input, but ORM escapes it to prevent SQL injection.

Execution Table

Step	Action	Input Value	ORM Behavior	Generated SQL Snippet
1	Receive user input	1 OR 1=1	Stores input as string	N/A
2	Pass input to filter	"1 OR 1=1"	Escapes input safely	WHERE username = '1 OR 1=1'
3	Generate SQL query	N/A	Uses parameterized query	SELECT * FROM user WHERE username = %s
4	Execute query	N/A	Database treats input as value	No injection occurs
5	Return results	N/A	Safe results returned	Results matching username='1 OR 1=1' (likely none)

💡 Execution stops after safe query runs; no SQL injection possible because input is escaped.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
user_input	None	"1 OR 1=1"	"1 OR 1=1"	"1 OR 1=1"	"1 OR 1=1"
result.query	None	None	Query object with escaped input	Final SQL query with parameter	Final SQL query with parameter

Key Moments - 2 Insights

Why doesn't the input '1 OR 1=1' cause a SQL injection?

Because the ORM escapes the input and uses parameterized queries, it treats the input as a plain string value, not executable SQL. See execution_table step 3 and 4.

What happens if we directly concatenate user input into raw SQL?

Direct concatenation can let malicious input run as SQL code, causing injection. The ORM avoids this by escaping and parameterizing inputs automatically.

Visual Quiz - 3 Questions

Look at the execution_table, what SQL snippet does the ORM generate for the input at step 2?

A WHERE username = 1 OR 1=1

B WHERE username = '1 OR 1=1'

C WHERE username = 1

D WHERE username = %s

💡 Hint

Check the 'Generated SQL Snippet' column at step 2 in execution_table.

At which step does the ORM ensure the input is treated as a value, not code?

A Step 1

B Step 2

C Step 4

D Step 3

💡 Hint

Look at the 'ORM Behavior' and 'Generated SQL Snippet' columns for step 4.

If user_input was concatenated directly into raw SQL, what risk would increase?

A Risk of SQL injection

B No risk, same safety

C Risk of syntax error only

D Risk of slow query

💡 Hint

Refer to key_moments about direct concatenation risks.

Concept Snapshot

Use ORM queries to handle user input safely.
ORM escapes inputs and uses parameterized queries.
This prevents SQL injection attacks.
Never build raw SQL by concatenating user input.
Always trust ORM to generate safe SQL.

Full Transcript

This visual trace shows how Django's ORM protects against SQL injection. When user input like '1 OR 1=1' is passed to a filter, the ORM escapes it and uses parameterized queries. The database treats the input as a string value, not executable code. This prevents attackers from injecting harmful SQL. The execution table steps through receiving input, escaping it, generating the query, executing safely, and returning results. Variable tracking shows the input stays unchanged but is safely handled. Key moments clarify why injection doesn't happen and warn against raw SQL concatenation. The quiz tests understanding of how ORM escapes input and when the input is treated safely. The snapshot reminds to always use ORM for queries with user input to avoid injection risks.

Practice

1. Which of the following best explains how Django ORM protects against SQL injection?

easy

A. It automatically escapes user inputs when building queries.

B. It disables all user inputs by default.

C. It requires manual escaping of inputs in queries.

D. It converts all queries to raw SQL strings.

Solution

1. Step 1: Understand Django ORM query building

   Django ORM builds SQL queries by safely escaping user inputs automatically.

2. Step 2: Compare options with ORM behavior

   Only automatic escaping matches Django ORM's protection against SQL injection.

3. Final Answer:

   It automatically escapes user inputs when building queries. -> Option A

4. Quick Check:

   Django ORM auto-escapes inputs = C [OK]

Hint: Remember: ORM escapes inputs automatically to prevent injection [OK]

Common Mistakes:

• Thinking ORM disables inputs
• Believing manual escaping is needed
• Assuming ORM uses raw SQL strings

2. Which Django ORM method is safe to use for filtering records with user input?

easy

A. Model.objects.raw(f"SELECT * FROM table WHERE name = '{user_input}'")

B. Model.objects.filter("name = " + user_input)

C. Model.objects.filter(name=user_input)

D. Model.objects.execute_sql("SELECT * FROM table WHERE name = " + user_input)

Solution

1. Step 1: Identify safe ORM filtering syntax

   Model.objects.filter(name=user_input) uses ORM's parameter binding and escapes input safely.

2. Step 2: Analyze other options for unsafe practices

   Options A, B, and C build raw SQL strings or invalid syntax, risking injection.

3. Final Answer:

   Model.objects.filter(name=user_input) -> Option C

4. Quick Check:

   Use filter() with keyword args for safe queries = D [OK]

Hint: Use filter() with keyword arguments, not raw SQL strings [OK]

Common Mistakes:

• Using raw SQL with string concatenation
• Passing raw SQL strings to filter()
• Ignoring ORM's parameter binding

3. What will be the output of this Django ORM query if user_input = "Robert'); DROP TABLE users;--"?

users = User.objects.filter(username=user_input)
print(users.query)

medium

A. A raw SQL query that deletes the users table

B. An empty query with no filtering

C. A syntax error due to unescaped quotes

D. A safe SQL query with escaped input preventing injection

Solution

1. Step 1: Understand ORM query with dangerous input

   ORM escapes dangerous characters in user_input to prevent SQL injection.

2. Step 2: Analyze printed query behavior

   Printed query shows safe SQL with escaped input, not raw injection or errors.

3. Final Answer:

   A safe SQL query with escaped input preventing injection -> Option D

4. Quick Check:

   ORM escapes dangerous input = B [OK]

Hint: ORM escapes dangerous input, so injection won't happen [OK]

Common Mistakes:

• Assuming raw SQL runs as is
• Expecting syntax errors from quotes
• Thinking ORM ignores dangerous input

4. Identify the error in this Django ORM code that tries to prevent SQL injection:

query = "SELECT * FROM users WHERE username = '%s'" % user_input
users = User.objects.raw(query)

medium

A. The raw() method automatically escapes inputs, so no error.

B. Using raw SQL with string formatting allows SQL injection.

C. The filter() method should be used instead of raw().

D. The query string is missing parameter placeholders.

Solution

1. Step 1: Analyze string formatting with user input

   Using % formatting inserts user_input directly, risking SQL injection.

2. Step 2: Understand raw() method behavior

   raw() executes raw SQL without escaping, so injection risk remains.

3. Final Answer:

   Using raw SQL with string formatting allows SQL injection. -> Option B

4. Quick Check:

   String formatting + raw() = injection risk = A [OK]

Hint: Never build raw SQL with string formatting; use ORM methods [OK]

Common Mistakes:

• Assuming raw() escapes inputs
• Using raw SQL instead of filter()
• Ignoring injection risk in string formatting

5. You want to safely filter users by email domain using Django ORM. Which approach correctly prevents SQL injection?

user_domain = request.GET.get('domain')
# Which code is safe?
A) User.objects.filter(email__endswith=user_domain)
B) User.objects.raw(f"SELECT * FROM users WHERE email LIKE '%{user_domain}'")
C) User.objects.filter(email__endswith='%' + user_domain)
D) User.objects.raw("SELECT * FROM users WHERE email LIKE '%" + user_domain + "'")

hard

A. User.objects.filter(email__endswith=user_domain)

B. User.objects.raw(f"SELECT * FROM users WHERE email LIKE '%{user_domain}'")

C. User.objects.filter(email__endswith='%' + user_domain)

D. User.objects.raw("SELECT * FROM users WHERE email LIKE '%" + user_domain + "'")

Solution

1. Step 1: Identify safe ORM filtering for email domain

   Using filter() with email__endswith=user_domain safely escapes input and builds query.

2. Step 2: Analyze raw() and string concatenation risks

   Options B and D use raw SQL with string interpolation, risking injection. User.objects.filter(email__endswith='%' + user_domain) incorrectly adds '%' in Python string, not ORM pattern.

3. Final Answer:

   User.objects.filter(email__endswith=user_domain) -> Option A

4. Quick Check:

   Use ORM filter with lookup for safe input handling = A [OK]

Hint: Use ORM lookups like __endswith, avoid raw SQL with user input [OK]

Common Mistakes:

• Using raw SQL with user input directly
• Adding SQL wildcards in Python strings
• Ignoring ORM's safe query building