Certified Ethical Hacker Exam Prep by By Michael Gregg

Author:By Michael Gregg [Gregg, By Michael]
Language: rus
Format: epub
ISBN: 0789735318
Publisher: Que
Published: 0101-01-01T00:00:00+00:00

Eavesdropping

Eavesdropping is one of these basic problems. If the attacker is within range, he can simply intercept radio signals and decode the data being transmitted. Nothing more than a wireless sniffer and the ability to place the wireless NIC into promiscuous mode is required. Remember that promiscuous mode means that the adapter has the capability to capture all packets, not just those addressed to the client. If the hacker uses an antenna, he can be even farther away, which makes these attacks hard to detect and prevent. Besides giving the hacker the ability to gather information about the network and its structure, protocols such as File Transfer Protocol (FTP), Telnet, and Simple Mail Transport Protocol (SMTP) that transmit username and passwords in clear text are highly vulnerable. Anything that is not encrypted is vulnerable to attack. Even if encryption is being used, a hacker eavesdropping on a network is still presented with the cipher text, which can be stored, analyzed, and potentially cracked at a later time. Would you really feel safe knowing that hackers have the NT LanMan (NTLM) password hashes? Programs such as L0phtcrack and John the Ripper can easily crack weak passwords if given the hash. If the hacker is limited in what he can sniff, he can always attempt active sniffing. Active sniffing, as discussed in Chapter 7, "Sniffers, Session Hijacking, and Denial of Service," involves Address Resolution Protocol (ARP) poisoning.

Exam Alert

ARP poisoning allows an attacker to overcome a switch's segmentation and eavesdrop on all local communication.

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