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 Incompleto
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.
Definição
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.
Impacto no mundo real
Real-world CVEs caused by CWE-749
-
arbitrary Java code execution via exposed method
-
security tool ActiveX control allows download or upload of files
Como os atacantes a exploram
Trajeto do atacante passo a passo
- 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.
Exemplo de código vulnerável
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) {...}
} Payload do atacante
A call into native code can then be initiated by passing parameters within the URL:
window.location = examplescheme://method?parameter=value Exemplo de código seguro
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.
Lista de verificação de prevenção
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.
Sinais de deteção
How to detect CWE-749
O Plexicus deteta automaticamente o CWE-749 e abre um PR de correção em menos de 60 segundos.
O Codex Remedium analisa cada commit, identifica esta fraqueza exata e entrega um pull request pronto para revisão com o patch. Sem tickets. Sem transferências.
Perguntas frequentes O que é o CWE-749?
Qual a gravidade do CWE-749?
Que linguagens ou plataformas são afetadas pelo CWE-749?
Como posso prevenir o CWE-749?
Como é que o Plexicus deteta e corrige o CWE-749?
Onde posso saber mais sobre o CWE-749?
Frequently asked questions
O que é o 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.
Qual a gravidade do CWE-749?
A MITRE classifica a probabilidade de exploração como Baixa — a exploração é pouco comum, mas a fraqueza deve mesmo assim ser corrigida quando descoberta.
Que linguagens ou plataformas são afetadas pelo CWE-749?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o CWE-749?
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…
Como é que o Plexicus deteta e corrige o CWE-749?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-749 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.
Onde posso saber mais sobre o CWE-749?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/749.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-749
CWE-284 Pai
Improper Access Control
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Insufficient Granularity of Access Control
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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 Irmão
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 Irmão
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 Irmão
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 Irmão
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 Irmão
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…
Recursos
Further reading
- MITRE — CWE-749 oficial 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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