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-923 Class Incomplete
Improper Restriction of Communication Channel to Intended Endpoints
This vulnerability occurs when a system opens a communication channel for a sensitive task but fails to properly verify that it's actually talking to the correct, intended destination. This allows a…
Definition
What is CWE-923?
This vulnerability occurs when a system opens a communication channel for a sensitive task but fails to properly verify that it's actually talking to the correct, intended destination. This allows a malicious actor to impersonate the legitimate endpoint.
Attackers can exploit this flaw by spoofing or redirecting the connection to a system they control. Once they successfully impersonate the intended endpoint, they gain the same level of access and privileges, potentially leading to data theft, unauthorized actions, or full system compromise.
While this commonly affects client-server authentication over networks, the core issue applies to any communication channel. This includes inter-process communication (IPC), cloud service APIs, container orchestration, and device-to-device links, wherever a trusted endpoint is assumed but not rigorously confirmed.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-923
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S-bus functionality in a home automation product performs access control using an IP allowlist, which can be bypassed by a forged IP address.
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A troubleshooting tool exposes a web server on a random port between 9000-65535 that could be used for information gathering
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A WAN interface on a router has firewall restrictions enabled for IPv4, but it does not for IPv6, which is enabled by default
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Product has a Silverlight cross-domain policy that does not restrict access to another application, which allows remote attackers to bypass the Same Origin Policy.
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Mobile banking application does not verify hostname, leading to financial loss.
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chain: incorrect "goto" in Apple SSL product bypasses certificate validation, allowing Adversry-in-the-Middle (AITM) attack (Apple "goto fail" bug). CWE-705 (Incorrect Control Flow Scoping) -> CWE-561 (Dead Code) -> CWE-295 (Improper Certificate Validation) -> CWE-393 (Return of Wrong Status Code) -> CWE-300 (Channel Accessible by Non-Endpoint).
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DNS server can accept DNS updates from hosts that it did not query, leading to cache poisoning
Wie Angreifer es ausnutzen
Angreiferpfad Schritt für Schritt
- 1
These cross-domain policy files mean to allow Flash and Silverlight applications hosted on other domains to access its data:
- 2
Flash crossdomain.xml :
- 3
Silverlight clientaccesspolicy.xml :
- 4
These entries are far too permissive, allowing any Flash or Silverlight application to send requests. A malicious application hosted on any other web site will be able to send requests on behalf of any user tricked into executing it.
- 5
This Android application will remove a user account when it receives an intent to do so:
Verwundbares Codebeispiel
Vulnerable XML
Flash crossdomain.xml :
<cross-domain-policy xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://www.adobe.com/xml/schemas/PolicyFile.xsd">
<allow-access-from domain="*.example.com"/>
<allow-access-from domain="*"/>
</cross-domain-policy> Sicheres Codebeispiel
Secure 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-923
- 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-923
Plexicus erkennt CWE-923 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-923?
Wie gravierend ist CWE-923?
Welche Sprachen oder Plattformen sind von CWE-923 betroffen?
Wie kann ich CWE-923 verhindern?
Wie erkennt und behebt Plexicus CWE-923?
Wo erfahre ich mehr über CWE-923?
Frequently asked questions
Was ist CWE-923?
This vulnerability occurs when a system opens a communication channel for a sensitive task but fails to properly verify that it's actually talking to the correct, intended destination. This allows a malicious actor to impersonate the legitimate endpoint.
Wie gravierend ist CWE-923?
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-923 betroffen?
MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.
Wie kann ich CWE-923 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-923?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-923 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-923?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/923.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-923
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
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