COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONLive MITRE record

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.

Abstraction

Detailed

Typical severity

Low

Likelihood of attack

Medium

Understand the attack

What is this attack pattern?

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.

Extended description

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.

Execution flow

How does the attack proceed, step by step?

1

Experiment

Attack step

An adversary sends UDP packets to target ports.

Attack step

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.

Requirements

What does the attack require?

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.

Skills required

Not stated in the MITRE record.

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.

Impact

What does a successful attack lead to?

Other

Affected scopes: Confidentiality

Bypass Protection MechanismHide Activities

Affected scopes: Confidentiality, Access Control, Authorization

Defence

How is it prevented and mitigated?

1
Firewalls or ACLs which block egress ICMP error types effectively prevent UDP scans from returning any useful information.
2
UDP scanning is complicated by rate limiting mechanisms governing ICMP error messages.
CAPEC-308: UDP Scan — DayBreach Saldırı Sözlüğü · DayBreach