Name |
IP (DF) 'Don't Fragment Bit' Echoing Probe |
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Likelyhood of attack |
Typical severity |
Medium |
Low |
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Summary |
This OS fingerprinting probe tests to determine if the remote host echoes back the IP 'DF' (Don't Fragment) bit in a response packet. An attacker sends a UDP datagram with the DF bit set to a closed port on the remote host to observe whether the 'DF' bit is set in the response packet. Some operating systems will echo the bit in the ICMP error message while others will zero out the bit in the response packet. |
Prerequisites |
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Solutions | |
Related Weaknesses |
CWE ID
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Description
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CWE-200 |
Exposure of Sensitive Information to an Unauthorized Actor |
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Related CAPECS |
CAPEC ID
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Description
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CAPEC-312 |
An adversary engages in activity to detect the operating system or firmware version of a remote target by interrogating a device, server, or platform with a probe designed to solicit behavior that will reveal information about the operating systems or firmware in the environment. Operating System detection is possible because implementations of common protocols (Such as IP or TCP) differ in distinct ways. While the implementation differences are not sufficient to 'break' compatibility with the protocol the differences are detectable because the target will respond in unique ways to specific probing activity that breaks the semantic or logical rules of packet construction for a protocol. Different operating systems will have a unique response to the anomalous input, providing the basis to fingerprint the OS behavior. This type of OS fingerprinting can distinguish between operating system types and versions. |
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