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.)
CWE-749 Base Incomplete
Exposed Dangerous Method or Function
This vulnerability occurs when a software component exposes an API or interface containing a high-risk function that lacks proper access controls, allowing unauthorized actors to trigger it.
Definition
What is CWE-749?
This vulnerability occurs when a software component exposes an API or interface containing a high-risk function that lacks proper access controls, allowing unauthorized actors to trigger it.
Exposing an unsafe function through a public interface creates a flexible attack surface. The danger stems not from the function itself, but from who can access it. Attackers can exploit this to trigger unintended behaviors—like file deletion, system commands, or data corruption—depending on what the exposed method does. This pattern applies broadly across technologies, including ActiveX controls, Java methods, IOCTLs, and REST API endpoints.
The exposure typically happens in two scenarios: either the function was never meant to be publicly accessible during design, or it was intended only for a specific, trusted client (like a single website) but was improperly scoped. In both cases, the core failure is missing or inadequate authorization checks that should restrict access to privileged or internal operations.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-749
-
arbitrary Java code execution via exposed method
-
security tool ActiveX control allows download or upload of files
Wie Angreifer es ausnutzen
Angreiferpfad Schritt für Schritt
- 1
In the following Java example the method removeDatabase will delete the database with the name specified in the input parameter.
- 2
The method in this example is declared public and therefore is exposed to any class in the application. Deleting a database should be considered a critical operation within an application and access to this potentially dangerous method should be restricted. Within Java this can be accomplished simply by declaring the method private thereby exposing it only to the enclosing class as in the following example.
- 3
These Android and iOS applications intercept URL loading within a WebView and perform special actions if a particular URL scheme is used, thus allowing the Javascript within the WebView to communicate with the application:
- 4
A call into native code can then be initiated by passing parameters within the URL:
- 5
Because the application does not check the source, a malicious website loaded within this WebView has the same access to the API as a trusted site.
Verwundbares Codebeispiel
Vulnerable Java
In the following Java example the method removeDatabase will delete the database with the name specified in the input parameter.
public void removeDatabase(String databaseName) {
try {
Statement stmt = conn.createStatement();
stmt.execute("DROP DATABASE " + databaseName);
} catch (SQLException ex) {...}
} Angreifer-Payload
A call into native code can then be initiated by passing parameters within the URL:
window.location = examplescheme://method?parameter=value Sicheres Codebeispiel
Secure Java
The method in this example is declared public and therefore is exposed to any class in the application. Deleting a database should be considered a critical operation within an application and access to this potentially dangerous method should be restricted. Within Java this can be accomplished simply by declaring the method private thereby exposing it only to the enclosing class as in the following example.
private void removeDatabase(String databaseName) {
try {
Statement stmt = conn.createStatement();
stmt.execute("DROP DATABASE " + databaseName);
} catch (SQLException ex) {...}
} 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-749
- Architecture and Design If you must expose a method, make sure to perform input validation on all arguments, limit access to authorized parties, and protect against all possible vulnerabilities.
- Architecture and Design / Implementation Identify all exposed functionality. Explicitly list all functionality that must be exposed to some user or set of users. Identify which functionality may be: - accessible to all users - restricted to a small set of privileged users - prevented from being directly accessible at all Ensure that the implemented code follows these expectations. This includes setting the appropriate access modifiers where applicable (public, private, protected, etc.) or not marking ActiveX controls safe-for-scripting.
Erkennungssignale
How to detect CWE-749
Plexicus erkennt CWE-749 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.
Häufig gestellte Fragen Was ist CWE-749?
Wie gravierend ist CWE-749?
Welche Sprachen oder Plattformen sind von CWE-749 betroffen?
Wie kann ich CWE-749 verhindern?
Wie erkennt und behebt Plexicus CWE-749?
Wo erfahre ich mehr über CWE-749?
Frequently asked questions
Was ist CWE-749?
This vulnerability occurs when a software component exposes an API or interface containing a high-risk function that lacks proper access controls, allowing unauthorized actors to trigger it.
Wie gravierend ist CWE-749?
MITRE stuft die Exploit-Wahrscheinlichkeit als niedrig ein — eine Ausnutzung ist selten, die Schwachstelle sollte aber dennoch behoben werden, sobald sie entdeckt wird.
Welche Sprachen oder Plattformen sind von CWE-749 betroffen?
MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.
Wie kann ich CWE-749 verhindern?
If you must expose a method, make sure to perform input validation on all arguments, limit access to authorized parties, and protect against all possible vulnerabilities. Identify all exposed functionality. Explicitly list all functionality that must be exposed to some user or set of users. Identify which functionality may be: - accessible to all users - restricted to a small set of privileged users - prevented from being directly accessible at all Ensure that the implemented code follows…
Wie erkennt und behebt Plexicus CWE-749?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-749 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-749?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/749.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-749
CWE-284 Parent
Improper Access Control
The software fails to properly limit who can access a resource, allowing unauthorized users or systems to interact with it.
CWE-1191 Sibling
On-Chip Debug and Test Interface With Improper Access Control
This vulnerability occurs when a hardware chip's debug or test interface (like JTAG) lacks proper access controls. Without correct…
CWE-1220 Sibling
Insufficient Granularity of Access Control
This vulnerability occurs when a system's access controls are too broad, allowing unauthorized users or processes to read or modify…
CWE-1224 Sibling
Improper Restriction of Write-Once Bit Fields
This vulnerability occurs when hardware write-once protection mechanisms, often called 'sticky bits,' are incorrectly implemented,…
CWE-1231 Sibling
Improper Prevention of Lock Bit Modification
This vulnerability occurs when hardware or firmware uses a lock bit to protect critical system registers or memory regions, but fails to…
CWE-1233 Sibling
Security-Sensitive Hardware Controls with Missing Lock Bit Protection
This vulnerability occurs when a hardware device uses a lock bit to protect critical configuration registers, but the lock fails to…
CWE-1252 Sibling
CPU Hardware Not Configured to Support Exclusivity of Write and Execute Operations
This vulnerability occurs when a CPU's hardware is not set up to enforce a strict separation between writing data to memory and executing…
CWE-1257 Sibling
Improper Access Control Applied to Mirrored or Aliased Memory Regions
This vulnerability occurs when a hardware design maps the same physical memory to multiple addresses (aliasing or mirroring) but fails to…
CWE-1259 Sibling
Improper Restriction of Security Token Assignment
This vulnerability occurs when a System-on-a-Chip (SoC) fails to properly secure its Security Token mechanism. These tokens control which…
Ressourcen
Further reading
- MITRE — offizielle CWE-749 https://cwe.mitre.org/data/definitions/749.html
- Developing Secure ActiveX Controls https://learn.microsoft.com/en-us/previous-versions//ms533046(v=vs.85)?redirectedfrom=MSDN
- How to stop an ActiveX control from running in Internet Explorer https://support.microsoft.com/en-us/help/240797/how-to-stop-an-activex-control-from-running-in-internet-explorer
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