Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

Opis

The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. Without sufficient removal or quoting of SQL syntax in user-controllable inputs, the generated SQL query can cause those inputs to be interpreted as SQL instead of ordinary user data.

Inne nazwy

SQL injection

a common attack-oriented phrase

SQLi

a common abbreviation for "SQL injection"

Skutki

• Confidentiality, Integrity, Availability

  Execute Unauthorized Code or Commands

  Adversaries could execute system commands, typically by changing the SQL statement to redirect output to a file that can then be executed.

• Confidentiality

  Read Application Data

  Since SQL databases generally hold sensitive data, loss of confidentiality is a frequent problem with SQL injection vulnerabilities.

• Authentication

  Gain Privileges or Assume Identity; Bypass Protection Mechanism

  If poor SQL commands are used to check user names and passwords or perform other kinds of authentication, it may be possible to connect to the product as another user with no previous knowledge of the password.

• Access Control

  Bypass Protection Mechanism

  If authorization information is held in a SQL database, it may be possible to change this information through the successful exploitation of a SQL injection vulnerability.

• Integrity

  Modify Application Data

  Just as it may be possible to read sensitive information, it is also possible to modify or even delete this information with a SQL injection attack.

Zapobieganie

• Architecture and Design · Libraries or Frameworks

  Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].

  For example, consider using persistence layers such as Hibernate or Enterprise Java Beans, which can provide significant protection against SQL injection if used properly.

• Architecture and Design · Parameterization

  If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.

  Process SQL queries using prepared statements, parameterized queries, or stored procedures. These features should accept parameters or variables and support strong typing. Do not dynamically construct and execute query strings within these features using "exec" or similar functionality, since this may re-introduce the possibility of SQL injection. [REF-867]

• Architecture and Design, Operation · Environment Hardening

  Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

  Specifically, follow the principle of least privilege when creating user accounts to a SQL database. The database users should only have the minimum privileges necessary to use their account. If the requirements of the system indicate that a user can read and modify their own data, then limit their privileges so they cannot read/write others' data. Use the strictest permissions possible on all database objects, such as execute-only for stored procedures.

• Architecture and Design

  For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

• Implementation · Output Encoding

  While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).

  Instead of building a new implementation, such features may be available in the database or programming language. For example, the Oracle DBMS_ASSERT package can check or enforce that parameters have certain properties that make them less vulnerable to SQL injection. For MySQL, the mysql_real_escape_string() API function is available in both C and PHP.

• Implementation · Input Validation

  Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

  When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

  Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

  When constructing SQL query strings, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. This will indirectly limit the scope of an attack, but this technique is less important than proper output encoding and escaping.

  Note that proper output encoding, escaping, and quoting is the most effective solution for preventing SQL injection, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent SQL injection, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, the name "O'Reilly" would likely pass the validation step, since it is a common last name in the English language. However, it cannot be directly inserted into the database because it contains the "'" apostrophe character, which would need to be escaped or otherwise handled. In this case, stripping the apostrophe might reduce the risk of SQL injection, but it would produce incorrect behavior because the wrong name would be recorded.

  When feasible, it may be safest to disallow meta-characters entirely, instead of escaping them. This will provide some defense in depth. After the data is entered into the database, later processes may neglect to escape meta-characters before use, and you may not have control over those processes.

• Architecture and Design · Enforcement by Conversion

  When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.

• Implementation

  Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.

  If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.

  Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.

  In the context of SQL Injection, error messages revealing the structure of a SQL query can help attackers tailor successful attack strings.

• Operation · Firewall

  Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481.

  Skuteczność: Moderate

• Operation, Implementation · Environment Hardening

  When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.

Przykłady podatności

• CVE-2024-6847 SQL injection in AI chatbot via a conversation message
• CVE-2025-26794 SQL injection in e-mail agent through SQLite integration
• CVE-2023-32530 SQL injection in security product dashboard using crafted certificate fields
• CVE-2021-42258 SQL injection in time and billing software, as exploited in the wild per CISA KEV.
• CVE-2021-27101 SQL injection in file-transfer system via a crafted Host header, as exploited in the wild per CISA KEV.
• CVE-2020-12271 SQL injection in firewall product's admin interface or user portal, as exploited in the wild per CISA KEV.
• CVE-2019-3792 An automation system written in Go contains an API that is vulnerable to SQL injection allowing the attacker to read privileged data.
• CVE-2004-0366 chain: SQL injection in library intended for database authentication allows SQL injection and authentication bypass.
• CVE-2008-2790 SQL injection through an ID that was supposed to be numeric.
• CVE-2008-2223 SQL injection through an ID that was supposed to be numeric.
• CVE-2007-6602 SQL injection via user name.
• CVE-2008-5817 SQL injection via user name or password fields.
• CVE-2003-0377 SQL injection in security product, using a crafted group name.
• CVE-2008-2380 SQL injection in authentication library.
• CVE-2017-11508 SQL injection in vulnerability management and reporting tool, using a crafted password.

Słabość nadrzędna

• CWE-943 Improper Neutralization of Special Elements in Data Query Logic
• CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Słabości podrzędne

• CWE-564 SQL Injection: Hibernate

Kiedy powstaje

• Implementation — REALIZATION: This weakness is caused during implementation of an architectural security tactic.
• Implementation — This weakness typically appears in data-rich applications that save user inputs in a database.

Dotyczy

Not Language-Specific, SQL, Database Server

Uwagi

SQL injection can be resultant from special character mismanagement, MAID, or denylist/allowlist problems. It can be primary to authentication errors.

Źródła

1. NT Web Technology Vulnerabilities — rain.forest.puppy, Phrack Issue 54, Volume 8, 1998
2. 24 Deadly Sins of Software Security — Michael Howard, David LeBlanc, John Viega, "Sin 1: SQL Injection." Page 3, McGraw-Hill, 2010
3. Writing Secure Code — Michael Howard, David LeBlanc, Chapter 12, "Database Input Issues" Page 397, Microsoft Press, 2002
4. SQL Injection Prevention Cheat Sheet — OWASP
5. SQL Injection Attacks by Example — Steven Friedl, 2007
6. SQL Injection Cheat Sheet — Ferruh Mavituna, 2007
7. The Database Hacker's Handbook: Defending Database Servers — David Litchfield, Chris Anley, John Heasman, Bill Grindlay, Wiley, 2005
8. The Oracle Hacker's Handbook: Hacking and Defending Oracle — David Litchfield, Wiley, 2007
9. SQL Injection — Microsoft, 2008
10. SQL Injection Attack — Microsoft Security Vulnerability Research & Defense
11. Giving SQL Injection the Respect it Deserves — Michael Howard, 2008
12. Top 25 Series - Rank 2 - SQL Injection — Frank Kim, SANS Software Security Institute, 2010
13. Least Privilege — Sean Barnum, Michael Gegick, 2005
14. The Art of Software Security Assessment — Mark Dowd, John McDonald, Justin Schuh, Chapter 8, "SQL Queries", Page 431, Addison Wesley, 2006
15. The Art of Software Security Assessment — Mark Dowd, John McDonald, Justin Schuh, Chapter 17, "SQL Injection", Page 1061, Addison Wesley, 2006
16. Automated Source Code Security Measure (ASCSM) — Object Management Group (OMG), ASCSM-CWE-89, 2016
17. Secure by Design Alert: Eliminating SQL Injection Vulnerabilities in Software — Cybersecurity and Infrastructure Security Agency, 2024
18. State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation — Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, Rama S. Moorthy, 2014
19. D3FEND: Application Layer Firewall — D3FEND
20. D3FEND: D3-TL Trusted Library — D3FEND