Limiting database permissions helps prevent SQL injection (SQLi) attacks primarily by reducing the potential damage an attacker can cause if they manage to exploit a vulnerability. This approach is grounded in the principle of least privilege, which means granting users or application accounts only the minimum permissions necessary to perform their tasks, and no more.
Here is a detailed explanation of how limiting permissions helps:
**1. Restricts the Scope of Actions an Attacker Can Perform
If an application or user account connected to the database has only read-only access to specific tables, an attacker who exploits SQL injection through that account cannot modify, delete, or insert data. This containment limits the "blast radius" of the attack, preventing data corruption or unauthorized changes[3][9]. For example, if the account only needs to run SELECT queries, it should not have INSERT, UPDATE, DELETE, or administrative privileges.
**2. Prevents Unauthorized Data Access Beyond Necessity
By restricting database permissions to only the necessary tables and operations, attackers cannot access sensitive data outside the scope of the application's legitimate needs. This means even if SQL injection is successful, the attackerâs ability to extract or manipulate data is limited to what the compromised account can access[1][2][7].
**3. Limits Exploitation of Dangerous Database Features
Some database functionalities, like executing operating system commands or running unrestricted stored procedures, can be exploited if permissions are too broad. Limiting permissions disables or restricts access to such features, reducing the attack surface for SQL injection and related exploits[2][9].
**4. Reduces Risk of Privilege Escalation
If the database user runs with high privileges (e.g., admin or DBA roles), a successful SQL injection can lead to full control over the database, including creating or dropping tables, or even executing commands on the server. Limiting permissions prevents attackers from escalating their access beyond what the application legitimately requires[1][6][9].
**5. Supports Defense in Depth
While limiting permissions alone does not prevent SQL injection, it is a critical layer of defense that works alongside input validation, parameterized queries, stored procedures, and web application firewalls. This layered approach ensures that even if one control fails, others help contain the attack[3][7].
In summary, limiting database permissions reduces the potential impact of SQL injection by ensuring that compromised accounts cannot perform harmful actions beyond their intended scope. This containment helps prevent data loss, unauthorized data modification, and privilege escalation, making SQL injection attacks less damaging and easier to manage[1][2][3][6][9].
Citations:
[1] https://cheatsheetseries.owasp.org/cheatsheets/SQL_Injection_Prevention_Cheat_Sheet.html
[2] https://www.esecurityplanet.com/threats/how-to-prevent-sql-injection-attacks/
[3] https://www.legitsecurity.com/aspm-knowledge-base/how-to-prevent-sql-injection
[4] https://users.soe.ucsc.edu/~eaugusti/archive/365-spring16/365-files/lectures/365-lec14-security.pdf
[5] https://www.reddit.com/r/SQL/comments/1c5m63s/sql_injection_prevention_help/
[6] https://security.stackexchange.com/questions/90247/sql-injection-attack-why-not-just-adjust-permissions
[7] https://www.cloudflare.com/learning/security/threats/how-to-prevent-sql-injection/
[8] https://stackoverflow.com/questions/1263218/if-my-database-user-is-read-only-why-do-i-need-to-worry-about-sql-injection
[9] https://www.enterprisedb.com/blog/protecting-against-sql-injection