![]() ![]() It is simple a TCP send from the client to the router. The encrypted probe packet is then sent to telnet port (23) on the router using a TCP, or UDP socket in the standard manner.Ĭuriously, Netgear's Windows telnetEnable.exe program also includes the necessary support to decode packets incoming from the router, but there does not appear to be any two-way handshake implemented. The secret key used for Blowfish is “ AMBIT_TELNET_ENABLE+” concatenated by the password in the payload. The entire probe payload (including the reserved area, which is always null for this example) is then encrypted using the Blowfish algorithm, with reversed assumptions regarding the endianness of the data stream. The resulting 16 byte MD5 checksum/hash is then stored into the md5sum array of the probe payload. The MD5 checksum, or signature, is calculated for the contents of the probe payload MAC, username, and password fields, and is done using the normal three steps (MD5init, MD5update, MD5final) with the default RSA seed. The above payload formats are transformed by algorithms as follows: Payload is sent over TCP struct PAYLOAD_TCP_PLAINTEXTĬhar md5sum /* md5 hash 16 byte binary */Ĭhar mac /* null terminated string, 12 characters */Ĭhar username /* null terminated string */Ĭhar password /* null terminated string */įor newer Netgear routers (R6700, R7000, R7500) that use the modified TelnetEnable utility: The probe packet format in unencrypted form is as follows:įor older Netgear routers that use the original TelnetEnable utility: The TelnetEnable utility (see below) builds the probe packet using authentication data supplied on its command line. If the router accepts the probe packet and unlocks the CLI, then the CLI responds after a subsequent connection with a telnet client. ![]() The Netgear router CLI unlocking protocol establishes a TCP (for older Netgear routers), or UDP (for newer Netgear routers) connection on telnet port 23 to the router's LAN IP address, send an encrypted probe packet, then close the connection. ![]()
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