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.
Real-world impact
Real-world CVEs caused by CWE-749
-
arbitrary Java code execution via exposed method
-
security tool ActiveX control allows download or upload of files
How attackers exploit it
Step-by-step attacker path
- 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.
Vulnerable code example
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) {...}
} Attacker payload
A call into native code can then be initiated by passing parameters within the URL:
window.location = examplescheme://method?parameter=value Secure code example
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.
Prevention checklist
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.
Detection signals
How to detect CWE-749
Plexicus auto-detects CWE-749 and opens a fix PR in under 60 seconds.
Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.
Frequently asked questions What is CWE-749?
How serious is CWE-749?
What languages or platforms are affected by CWE-749?
How can I prevent CWE-749?
How does Plexicus detect and fix CWE-749?
Where can I learn more about CWE-749?
Frequently asked questions
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.
How serious is CWE-749?
MITRE rates the likelihood of exploit as Low — exploitation is uncommon, but the weakness should still be fixed when discovered.
What languages or platforms are affected by CWE-749?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent 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…
How does Plexicus detect and fix CWE-749?
Plexicus's SAST engine matches the data-flow signature for CWE-749 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-749?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/749.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
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…
Resources
Further reading
- MITRE — official 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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