CWE-943 Class Incomplete

Improper Neutralization of Special Elements in Data Query Logic

This vulnerability occurs when an application builds a query for a data store (like a database) but fails to properly sanitize user-controlled input. This allows an attacker to inject special…

Definition

What is CWE-943?

This vulnerability occurs when an application builds a query for a data store (like a database) but fails to properly sanitize user-controlled input. This allows an attacker to inject special elements that change the query's intended logic, potentially accessing or manipulating data in unauthorized ways.
Attackers can exploit this flaw to manipulate query logic in several harmful ways. They can alter search criteria to return different records, append extra commands, or change the number or order of results. This isn't just about stealing data; if your application logic assumes a specific result—like a single administrative user record—manipulating the query can cause it to incorrectly grant permissions or make flawed decisions based on tainted results. While SQL injection is the most well-known example, this risk applies to many query languages. NoSQL databases, LDAP queries, XPath, and other data querying systems (like HTSQL, DQL, or XQuery) are also vulnerable if input isn't properly neutralized. The core issue is trusting user input within any command that interprets logic, not just traditional SQL.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-943

  • CVE-2024-50672

    NoSQL injection in product for building eLearning courses allows password resets using a query processed by the Mongoose find function

  • CVE-2021-20736

    NoSQL injection in team collaboration product

  • CVE-2020-35666

    NoSQL injection in a PaaS platform using a MongoDB operator

  • CVE-2014-2503

    Injection using Documentum Query Language (DQL)

  • CVE-2014-2508

    Injection using Documentum Query Language (DQL)

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

  1. 1

    The following code dynamically constructs and executes a SQL query that searches for items matching a specified name. The query restricts the items displayed to those where owner matches the user name of the currently-authenticated user.

  2. 2

    The query that this code intends to execute follows:

  3. 3

    However, because the query is constructed dynamically by concatenating a constant base query string and a user input string, the query only behaves correctly if itemName does not contain a single-quote character. If an attacker with the user name wiley enters the string:

  4. 4

    for itemName, then the query becomes the following:

  5. 5

    The addition of the:

Verwundbares Codebeispiel

Vulnerable C#

The following code dynamically constructs and executes a SQL query that searches for items matching a specified name. The query restricts the items displayed to those where owner matches the user name of the currently-authenticated user.

Verwundbar C# 
...
  string userName = ctx.getAuthenticatedUserName();
  string query = "SELECT * FROM items WHERE owner = '" + userName + "' AND itemname = '" + ItemName.Text + "'";
  sda = new SqlDataAdapter(query, conn);
  DataTable dt = new DataTable();
  sda.Fill(dt);
  ...
Angreifer-Payload

However, because the query is constructed dynamically by concatenating a constant base query string and a user input string, the query only behaves correctly if itemName does not contain a single-quote character. If an attacker with the user name wiley enters the string:

Angreifer-Payload 
name' OR 'a'='a
Sicheres Codebeispiel

Secure pseudo

Sicher pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Präventions-Checkliste

How to prevent CWE-943

  • Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
  • Implementation Validate input at trust boundaries; use allowlists, not denylists.
  • Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
  • Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
  • Operation Monitor logs for the runtime signals listed in the next section.
Erkennungssignale

How to detect CWE-943

Automated Static Analysis High

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Plexicus Auto-Fix

Plexicus erkennt CWE-943 automatisch und öffnet in unter 60 Sekunden einen Fix-PR.

Codex Remedium scannt jeden Commit, identifiziert genau diese Schwachstelle und liefert einen reviewer-ready Pull Request mit dem Patch. Keine Tickets. Keine Hand-offs.

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Häufig gestellte Fragen

Frequently asked questions

Was ist CWE-943?

This vulnerability occurs when an application builds a query for a data store (like a database) but fails to properly sanitize user-controlled input. This allows an attacker to inject special elements that change the query's intended logic, potentially accessing or manipulating data in unauthorized ways.

Wie gravierend ist CWE-943?

MITRE hat für diese Schwachstelle keine Exploit-Wahrscheinlichkeit veröffentlicht. Behandle sie als mittlere Auswirkung, bis dein Threat Model anderes belegt.

Welche Sprachen oder Plattformen sind von CWE-943 betroffen?

MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.

Wie kann ich CWE-943 verhindern?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

Wie erkennt und behebt Plexicus CWE-943?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-943 bei jedem Commit. Bei einem Treffer öffnet unser Codex-Remedium-Agent einen Fix-PR mit korrigiertem Code, Tests und einer einzeiligen Zusammenfassung für den Reviewer.

Wo erfahre ich mehr über CWE-943?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/943.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-943

CWE-74 Parent

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

This vulnerability occurs when an application uses untrusted external input to build a command, query, or data structure for another…

CWE-1236 Sibling

Improper Neutralization of Formula Elements in a CSV File

This vulnerability occurs when an application writes user-supplied data into a CSV file without properly sanitizing special characters.…

CWE-75 Sibling

Failure to Sanitize Special Elements into a Different Plane (Special Element Injection)

This vulnerability occurs when an application fails to properly filter or encode user-supplied data containing special characters or…

CWE-77 Sibling

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

This vulnerability occurs when an application builds a system command using untrusted user input without properly sanitizing it. An…

CWE-78 Sibling

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

OS Command Injection occurs when an application builds a system command using untrusted, external input without properly sanitizing it.…

CWE-79 Sibling

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

This vulnerability occurs when a web application fails to properly sanitize or encode user-supplied input before displaying it on a…

CWE-88 Sibling

Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

This vulnerability occurs when an application builds a command string for execution by another component, but fails to properly separate…

CWE-89 Sibling

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

SQL Injection occurs when an application builds a database query using untrusted user input without properly sanitizing it. This allows an…

CWE-91 Sibling

XML Injection (aka Blind XPath Injection)

XML Injection occurs when an application fails to properly validate or escape user-controlled input before including it in XML documents…

Ressourcen

Further reading

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