This installment on password cracking tools deals with Cain & Abel. This tool is a great resource for performing password audits on Windows based operating systems. “It allows easy recovery of various kind of passwords by sniffing the network, cracking encrypted passwords using Dictionary, Brute-Force and Cryptanalysis attacks, recording VoIP conversations, decoding scrambled passwords, revealing password boxes, uncovering cached passwords and analyzing routing protocols. The program does not exploit any software vulnerabilities or bugs that could not be fixed with little effort. It covers some security aspects/weakness present in protocol’s standards, authentication methods and caching mechanisms; its main purpose is the simplified recovery of passwords and credentials from various sources, however it also ships some “non standard” utilities for Microsoft Windows users.” The newest version allows for sniffing passwords in a switched environment. It does this by leveraging ARP poisoning.
When a computer connected to the Internet or a corporate environment it will send IP packets. But first, it must lookup which Media Access Control, or MAC, address to send to address that uniquely identifies each node of a network. In IEEE 802 networks, the Data Link Control (DLC) layer of the OSI Reference Model is divided into two sublayers: the Logical Link Control (LLC) layer and the Media Access Control (MAC) layer, This address bound to a specific piece of hardware such as a Network Interface Card (NIC). A switch uses these MAC addresses in order to keep track of which traffic goes where. Now, by sending spoofed ARP packets a switch can get confused and “puke” the ARP cache. What this means is that traffic to specific destination can be redirected. Note that this can only be done by someone on the same piece of wire. By doing this the traffic will be sent in a broadcast on all ports as the switch attempts to relearn the pathways. This permits Cain & Abel to sniff for passwords. Mind you, with lower powered switches what can eventually happen is that the switch will reset. Do NOT try this in any environment that you do not control or without permission for one you don’t.
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[tags]Cain & Abel, Password, Tool, Cracking[/tags]