An adversary uses a TCP XMAS scan
to determine if ports are closed on the target machine
. This scan type is accomplished by sending TCP segments with all possible flags set in the packet header, generating packets that are illegal based on RFC 793.
What is Xmas scan Nmap?
Nmap Xmas scan was considered a
stealthy scan which analyzes responses to Xmas packets to determine the nature of the replying device
. Each operating system or network device responds in a different way to Xmas packets revealing local information such as OS (Operating System), port state and more.
What is Xmas tree scan?
Christmas tree packets can be used as
a method of TCP/IP stack fingerprinting
, exposing the underlying nature of a TCP/IP stack by sending the packets and then awaiting and analyzing the responses. When used as part of scanning a system, the TCP header of a Christmas tree packet has the flags FIN, URG and PSH set.
What is the difference between Xmas scan null scan and FIN scan?
FIN A FIN scan is
similar to an XMAS scan
but sends a packet with just the FIN flag set. FIN scans receive the same response and have the same limitations as XMAS scans. NULL – A NULL scan is also similar to XMAS and FIN in its limitations and response, but it just sends a packet with no flags set.
What is TCP Xmas tree attack?
A Christmas Tree Attack is a very
well known attack that is designed to send a very specifically crafted TCP packet to a device on the network
. This crafting of the packet is one that turns on a bunch of flags.
Which Nmap flag can be used for Xmas tree scan?
In the Xmas scan, Nmap sends
packets with URG, FIN, and PSH flags
activated. This has the effect of “lighting the packet up like a Christmas tree” and can occasionally solicit a response from a firewalled system. Not all systems will respond to probes of this type.
Why are null FIN and Xmas scans generally used?
The NULL, FIN, and Xmas scans
clear the SYN bit and thus fly right through
those rules. Another advantage is that these scan types are a little more stealthy than even a SYN scan.
What is a stealth scan?
A stealth scan (sometimes known as a half open scan) is
much like a full open scan with a minor difference that makes it less suspicious on the victim’s device
. The primary difference is that a full TCP three-way handshake does not occur.
What is a TCP ACK scan?
The TCP ACK scanning technique
uses packets with the flag ACK on to try to determine if a port is filtered
. This technique comes handy when checking if the firewall protecting a host is stateful or stateless.
What is one reason for using a scan like an ACK scan?
One of the most interesting uses of ACK scanning is
to differentiate between stateful and stateless firewalls
. See the section called “ACK Scan” for how to do this and why you would want to. Sometimes a combination of scan types can be used to glean extra information from a system.
How does stealth scan work?
SYN or Stealth scanning makes use of this procedure by
sending a SYN packet and looking at the response
. If SYN/ACK is sent back, the port is open and the remote end is trying to open a TCP connection.
How does idle scan work?
The idle scan is a TCP port scan method that consists of
sending spoofed packets to a computer to find out what services are available
. This is accomplished by impersonating another computer whose network traffic is very slow or nonexistent (that is, not transmitting or receiving information).
What is fin packet?
TCP FIN packets are
sent to close a connection
. A packet in which both SYN and FIN flags are set should never exist. Therefore these packets might signify an attack on the device and should be blocked.
What is an Xmas attack?
It is a
type of attack where a specially crafted TCP packet is sent to the target device
. This attack is used as a reconnaissance technique to grab information about various operating systems. … Christmas tree packets are also known as kamikaze packets and lamp test segments.
How does ping of death attack work?
What is a ping of death attack. Ping of Death (a.k.a. PoD) is a type of Denial of Service (DoS) attack in which an attacker attempts to crash, destabilize, or freeze the targeted computer or service by sending malformed or
oversized packets using a simple ping command
.
What are flags in TCP?
In TCP connection, flags are
used to indicate a particular state of connection or to provide some additional useful information like troubleshooting purposes or to handle a control of a particular connection
. Most commonly used flags are “SYN”, “ACK” and “FIN”. Each flag corresponds to 1 bit information.
