CAPEC-308
UDP Scan
An adversary engages in UDP scanning to gather information about UDP port status on the target system. UDP scanning methods involve sending a UDP datagram to the target port and looking for evidence that the port is closed. Open UDP ports usually do not respond to UDP datagrams as there is no stateful mechanism within the protocol that requires building or establishing a session. Responses to UDP datagrams are therefore application specific and cannot be relied upon as a method of detecting an open port. UDP scanning relies heavily upon ICMP diagnostic messages in order to determine the status of a remote port.
On this page
During a UDP scan, a datagram is sent to a target port. If an 'ICMP Type 3 Port unreachable' error message is returned then the port is considered closed. Different types of ICMP messages can indicate a filtered port. UDP scanning is slower than TCP scanning. The protocol characteristics of UDP make port scanning inherently more difficult than with TCP, as well as dependent upon ICMP for accurate scanning. Due to ambiguities that can arise between open ports and filtered ports, UDP scanning results often require a high degree of interpretation and further testing to refine. In general, UDP scanning results are less reliable or accurate than TCP-based scanning.
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Explain the attack pattern CAPEC-308: UDP Scan: how it unfolds, what it needs and how to prevent and detect it in my systems. Use https://capec.mitre.org/data/definitions/308.html and https://cve.bz/cve/capec/308?via=ask-ai-copy, which lists recent CVEs with the weaknesses it exploits. Cite the sources.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this attack pattern's id and public links.
How the attack unfolds
Experiment
They probe what they found.
An adversary sends UDP packets to target ports.
An adversary uses the response from the target to determine the port's state. Whether a port responds to a UDP packet is dependant on what application is listening on that port. No response does not indicate the port is not open.
Prerequisites
The ability to send UDP datagrams to a host and receive ICMP error messages from that host. In cases where particular types of ICMP messaging is disallowed, the reliability of UDP scanning drops off sharply.
Resources required
The ability to craft custom UDP Packets for use during network reconnaissance. This can be accomplished via the use of a port scanner, or via socket manipulation in a programming or scripting language. Packet injection tools are also useful. It is also necessary to trap ICMP diagnostic messages during this process. Depending upon the method used it may be necessary to sniff the network in order to see the response.
Consequences
| Impact | Affects | Note |
|---|---|---|
| Other | Confidentiality | |
| Bypass Protection Mechanism, Hide Activities | Confidentiality, Access Control, Authorization |
Mitigations
Firewalls or ACLs which block egress ICMP error types effectively prevent UDP scans from returning any useful information.
UDP scanning is complicated by rate limiting mechanisms governing ICMP error messages.
Weaknesses it exploits
- CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
Recent CVEs with these weaknesses
- 4.3CVE-2026-124944
Information disclosure in the Marionette component. This vulnerability was fixed in Firefox 160.
- 4.3CVE-2026-124941
Information disclosure in the Security: RLBox component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.
- 4.3CVE-2026-124930
Information disclosure in the Address Bar component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.
- 4.3CVE-2026-124929
Information disclosure in the Layout: Form Controls component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.
- 4.3CVE-2026-124925
Information disclosure in the Layout component. This vulnerability was fixed in Firefox 160.
- 4.3CVE-2026-124909
Information disclosure in the Private Browsing component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.
- 5.3CVE-2026-96769
The Extend B2B - Companies and Users Management for WooCommerce plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 2.1.4 via the register_company_api. This makes it possible for unaut…
- 7.5CVE-2026-63644
bird-lg-go is a BIRD looking glass in Go. Prior to version 1.4.7, unsanitized input path enables arbitrary local file read, allowing an unauthenticated remote attacker to read sensitive files such as /etc/shadow and /root/.bash_history. Th…
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Related attack patterns
- Part of
- CAPEC-300 Port Scanning
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