Common Attack Pattern Enumeration and Classification
A Community Resource for Identifying and Understanding Attacks
An adversary uses a technique to generate an ICMP Error message (Port Unreachable, Destination Unreachable, Redirect, Source Quench, Time Exceeded, Parameter Problem) from a target and then analyze the amount of data returned or "Quoted" from the originating request that generated the ICMP error message. For this purpose "Port Unreachable" error messages are often used, as generating them requires the attacker to send a UDP datagram to a closed port on the target. The goal of this analysis to make inferences about the type of operating system or firmware that sent the error message in reply. This is useful for identifying unique characteristics of operating systems because the RFC-1122 expected behavior reads: "Every ICMP error message includes the Internet header and at least the first 8 data octets of the datagram that triggered the error; more than 8 octets MAY be sent [...]." This contrasts with RFC-792 expected behavior, which limited the quoted text to 64 bits (8 octets). Given the latitude in the specification the resulting RFC-1122 stack implementations often respond with a high degree of variability in the amount of data quoted in the error message because "older" or "legacy" stacks may comply with the RFC-792 specification, while other stacks may choose a longer format in accordance with RFC-1122. As a general rule most operating systems or firmware will quote the first 8 bytes of the datagram triggering the error, but some IP stacks will quote more than the first 8 bytes of data.
The table below shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
The table below shows the views that this attack pattern belongs to and top level categories within that view.
A tool capable of sending/receiving UDP datagram packets from a remote system to a closed port and receive an ICMP Error Message Type 3, "Port Unreachable..
The table below specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
A Related Weakness relationship associates a weakness with this attack pattern. Each association implies a weakness that must exist for a given attack to be successful. If multiple weaknesses are associated with the attack pattern, then any of the weaknesses (but not necessarily all) may be present for the attack to be successful. Each related weakness is identified by a CWE identifier.
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