/*************************************************************************** * ncrack_ssh.cc -- ncrack module for the SSH protocol * * * ***********************IMPORTANT NMAP LICENSE TERMS************************ * * * The Nmap Security Scanner is (C) 1996-2011 Insecure.Com LLC. Nmap is * * also a registered trademark of Insecure.Com LLC. This program is free * * software; you may redistribute and/or modify it under the terms of the * * GNU General Public License as published by the Free Software * * Foundation; Version 2 with the clarifications and exceptions described * * below. This guarantees your right to use, modify, and redistribute * * this software under certain conditions. If you wish to embed Nmap * * technology into proprietary software, we sell alternative licenses * * (contact sales@insecure.com). Dozens of software vendors already * * license Nmap technology such as host discovery, port scanning, OS * * detection, and version detection. * * * * Note that the GPL places important restrictions on "derived works", yet * * it does not provide a detailed definition of that term. To avoid * * misunderstandings, we consider an application to constitute a * * "derivative work" for the purpose of this license if it does any of the * * following: * * o Integrates source code from Nmap * * o Reads or includes Nmap copyrighted data files, such as * * nmap-os-db or nmap-service-probes. * * o Executes Nmap and parses the results (as opposed to typical shell or * * execution-menu apps, which simply display raw Nmap output and so are * * not derivative works.) * * o Integrates/includes/aggregates Nmap into a proprietary executable * * installer, such as those produced by InstallShield. * * o Links to a library or executes a program that does any of the above * * * * The term "Nmap" should be taken to also include any portions or derived * * works of Nmap. This list is not exclusive, but is meant to clarify our * * interpretation of derived works with some common examples. 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See the GNU * * General Public License v2.0 for more details at * * http://www.gnu.org/licenses/gpl-2.0.html , or in the COPYING file * * included with Nmap. * * * ***************************************************************************/ #include "ncrack.h" #include "nsock.h" #include "NcrackOps.h" #include "Service.h" #include "modules.h" #include /* OpenSSH include-files */ #include "opensshlib.h" #include "ssh2.h" #include "openssl/dh.h" #include "buffer.h" #include "sshbuf.h" #include "kex.h" #include "sshconnect.h" #include "packet.h" #include "misc.h" #include "cipher.h" #include "compat.h" #include "mac.h" #define SSH_TIMEOUT 20000 #define CLIENT_VERSION "SSH-2.0-OpenSSH_7.1\n" extern NcrackOps o; extern void ncrack_read_handler(nsock_pool nsp, nsock_event nse, void *mydata); extern void ncrack_write_handler(nsock_pool nsp, nsock_event nse, void *mydata); extern void ncrack_module_end(nsock_pool nsp, void *mydata); enum states { SSH_INIT, SSH_ID_EX, SSH_KEY, SSH_KEY2, SSH_KEY3, SSH_KEY4, SSH_AUTH, SSH_AUTH2, SSH_AUTH3, SSH_AUTH4, SSH_FINI }; static void ssh_free(Connection *con); static inline int ssh_loop_read(nsock_pool nsp, Connection *con, ncrack_ssh_state *info) { u_int packetlen = 0; /* If we have data in the I/O buffer, which means that we had previously * scheduled an nsock read event, then append the new data we got inside * the 'input' buffer which will be processed by the openssh library */ if (con->inbuf != NULL) { packetlen = con->inbuf->get_len(); //printf("packetlen read by nsock: %d\n", packetlen); if (packetlen > 0) { buffer_append(info->input, con->inbuf->get_dataptr(), packetlen); delete con->inbuf; con->inbuf = NULL; } //printf("info input length: %d \n", sshbuf_len(info->input)); } //printf("ncrack state %d\n", con->state); info->type = ncrackssh_ssh_packet_read(info); if (info->type == SSH_MSG_NONE) { //printf("ssh loop MSG NONE\n"); nsock_read(nsp, con->niod, ncrack_read_handler, SSH_TIMEOUT, con); return -1; } //printf("final input packet length %d\n", sshbuf_len(info->input)); delete con->inbuf; con->inbuf = NULL; return 0; } void ncrack_ssh(nsock_pool nsp, Connection *con) { nsock_iod nsi = con->niod; Service *serv = con->service; void *ioptr; u_int buflen; ncrack_ssh_state *info = NULL; con->ops_free = &ssh_free; if (con->misc_info) info = (ncrack_ssh_state *) con->misc_info; switch (con->state) { case SSH_INIT: con->state = SSH_ID_EX; con->misc_info = (ncrack_ssh_state *)safe_zalloc(sizeof(ncrack_ssh_state)); nsock_read(nsp, nsi, ncrack_read_handler, SSH_TIMEOUT, con); break; case SSH_ID_EX: buflen = con->inbuf->get_len(); ioptr = con->inbuf->get_dataptr(); if (!memsearch((const char *)ioptr, "\n", buflen)) { con->state = SSH_ID_EX; nsock_read(nsp, nsi, ncrack_read_handler, SSH_TIMEOUT, con); break; } if (strncmp((const char *)ioptr, "SSH-", 4)) { con->inbuf->clear(); con->state = SSH_ID_EX; nsock_read(nsp, nsi, ncrack_read_handler, SSH_TIMEOUT, con); break; } con->state = SSH_KEY; info->server_version_string = Strndup((char *)ioptr, buflen); ncrackssh_compat_datafellows(info); chop(info->server_version_string); /* NEVER forget to free allocated memory and also NULL-assign ptr */ delete con->inbuf; con->inbuf = NULL; if (con->outbuf) delete con->outbuf; con->outbuf = new Buf(); con->outbuf->append(CLIENT_VERSION, sizeof(CLIENT_VERSION)-1); info->client_version_string = Strndup( (const char *)con->outbuf->get_dataptr(), con->outbuf->get_len()); chop(info->client_version_string); nsock_write(nsp, nsi, ncrack_write_handler, SSH_TIMEOUT, con, (const char *)con->outbuf->get_dataptr(), con->outbuf->get_len()); break; case SSH_KEY: con->state = SSH_KEY2; /* sends "Key Exchange Init" */ /* Initialize cipher contexts and keys as well as internal opensshlib * buffers (input, output, incoming_packet, outgoing_packet) */ ssh_packet_set_connection(info); ncrackssh_ssh_kex2(info, info->client_version_string, info->server_version_string); nsock_write(nsp, nsi, ncrack_write_handler, SSH_TIMEOUT, con, (const char *)buffer_ptr(info->output), buffer_len(info->output)); buffer_consume(info->output, buffer_len(info->output)); break; case SSH_KEY2: if (ssh_loop_read(nsp, con, info) < 0) break; /* Receives: "Key Exchange Init" * Sends: "Diffie-Hellman GEX Request" */ con->state = SSH_KEY3; ncrackssh_kex_input_kexinit(info); nsock_write(nsp, nsi, ncrack_write_handler, SSH_TIMEOUT, con, (const char *)buffer_ptr(info->output), buffer_len(info->output)); buffer_consume(info->output, buffer_len(info->output)); break; case SSH_KEY3: if (ssh_loop_read(nsp, con, info) < 0) break; /* Receives: "Diffie-Hellman Key Exchange Reply" and * Sends: "Diffie-Hellman GEX Init" */ con->state = SSH_KEY4; if (info->kex->kex_type == KEX_ECDH_SHA2) { //printf("KEX ECDH SHA2 \n"); ncrackssh_input_kex_ecdh_reply(info); con->state = SSH_AUTH; } else if (info->kex->kex_type == KEX_DH_GRP1_SHA1 || info->kex->kex_type == KEX_DH_GRP14_SHA1) { //printf("dh client\n"); ncrackssh_input_kex_dh(info); con->state = SSH_AUTH; } else if (info->kex->kex_type == KEX_C25519_SHA256) { //printf("c25519 client\n"); ncrackssh_input_kex_c25519_reply(info); con->state = SSH_AUTH; } else { //printf("dh gex sha\n"); ncrackssh_input_kex_dh_gex_group(info); } nsock_write(nsp, nsi, ncrack_write_handler, SSH_TIMEOUT, con, (const char *)buffer_ptr(info->output), buffer_len(info->output)); buffer_consume(info->output, buffer_len(info->output)); break; case SSH_KEY4: if (ssh_loop_read(nsp, con, info) < 0) break; /* Receives: "Diffie-Hellman GEX Reply" and * Sends: "New keys" */ con->state = SSH_AUTH; ncrackssh_input_kex_dh_gex_reply(info); nsock_write(nsp, nsi, ncrack_write_handler, SSH_TIMEOUT, con, (const char *)buffer_ptr(info->output), buffer_len(info->output)); buffer_consume(info->output, buffer_len(info->output)); break; case SSH_AUTH: if (ssh_loop_read(nsp, con, info) < 0) break; /* Receives: "New keys" * Sends "Encrypted Request 1" */ con->state = SSH_AUTH2; ncrackssh_ssh_start_userauth2(info); nsock_write(nsp, nsi, ncrack_write_handler, SSH_TIMEOUT, con, (const char *)buffer_ptr(info->output), buffer_len(info->output)); buffer_consume(info->output, buffer_len(info->output)); break; case SSH_AUTH2: #if 0 if (info->kex->kex_type == KEX_DH_GEX_SHA1 || info->kex->kex_type == KEX_DH_GEX_SHA256) { printf("SSH AUTH 2 loop read \n"); if (ssh_loop_read(nsp, con, info) < 0) break; } #endif if (ssh_loop_read(nsp, con, info) < 0) break; con->state = SSH_AUTH3; /* * If server doesn't support "password" authentication method then * there is no point in doing any more attempts, so we can mark the * service as finished. */ if (ncrackssh_ssh_userauth2_service_rep(info) < 0) { serv->end.orly = true; if (con->outbuf) delete con->outbuf; //printf("Server error\n"); con->outbuf = new Buf(); Snprintf((char *)con->outbuf->get_dataptr(), DEFAULT_BUF_SIZE, "Server denied authentication request: %d", info->type); serv->end.reason = Strndup((const char *)con->outbuf->get_dataptr(), (size_t)strlen((const char *)con->outbuf->get_dataptr())); return ncrack_module_end(nsp, con); } /* Jump straight to next state */ nsock_timer_create(nsp, ncrack_timer_handler, 0, con); break; case SSH_AUTH3: /* * Sends credentials */ con->state = SSH_FINI; //printf("SSH AUTH 3 \n"); /* compare the current user with the previously saved on, so that if * we get another username in the same connection, we close the * connection because ssh doesn't let us change the username midway */ if (info->prev_user == NULL) { info->prev_user = con->user; //printf("null user: %s \n", info->prev_user); } else { if (info->prev_user != con->user) { //printf("CLOSING CONNECTION DUE TO DIFFERENT NAME\n"); con->force_close = true; con->close_reason = MODULE_ERR; return ncrack_module_end(nsp, con); } info->prev_user = con->user; //printf("prev_user %d \n", con->user); } ncrackssh_ssh_userauth2(info, con->user, con->pass); nsock_write(nsp, nsi, ncrack_write_handler, SSH_TIMEOUT, con, (const char *)buffer_ptr(info->output), buffer_len(info->output)); buffer_consume(info->output, buffer_len(info->output)); break; case SSH_FINI: if (ssh_loop_read(nsp, con, info) < 0) break; /* * If we get a disconnect message at this stage, then it probably * means that we reached the server's authentication limit per * connection. */ if (info->type == SSH2_MSG_DISCONNECT) { return ncrack_module_end(nsp, con); } if (info->type == SSH2_MSG_USERAUTH_SUCCESS) { //printf("succeed\n"); con->auth_success = true; con->force_close = true; } else if (info->type == SSH2_MSG_USERAUTH_FAILURE) { //printf("failed!\n"); con->state = SSH_AUTH3; } else if (info->type == SSH2_MSG_USERAUTH_BANNER) { //printf("Got banner!\n"); } return ncrack_module_end(nsp, con); } } static void ssh_free(Connection *con) { ncrack_ssh_state *p; if (!con->misc_info) return; p = (ncrack_ssh_state *)con->misc_info; if (p->kex) { if (p->kex->peer->alloc > 0) free(p->kex->peer->d); if (p->kex->my->alloc > 0) free(p->kex->my->d); if (p->kex->session_id) free(p->kex->session_id); free(p->kex); } /* Note that DH *dh has already been freed from * the openssh library */ /* 2 keys */ for (int i = 0; i < 2; i++) { if (p->newkeys[i]) { free(p->newkeys[i]->enc.iv); free(p->newkeys[i]->enc.key); free(p->newkeys[i]->mac.key); /* Without this specific call to cleanup the mac environment there * was a big memleak - reported by Valgrind to be starting from * mac_init() (opensshlib/mac.c). For some reason, no proper cleanup * was done and this explicit call for mac_clear() is needed. */ mac_clear(&p->newkeys[i]->mac); if (p->newkeys[i]->comp.name) free(p->newkeys[i]->comp.name); if (p->newkeys[i]->enc.name) free(p->newkeys[i]->enc.name); if (p->newkeys[i]->mac.name) free(p->newkeys[i]->mac.name); free(p->newkeys[i]); } } EVP_CIPHER_CTX_cleanup(&p->receive_context.evp); EVP_CIPHER_CTX_cleanup(&p->send_context.evp); buffer_free(p->input); buffer_free(p->output); buffer_free(p->incoming_packet); buffer_free(p->outgoing_packet); if (p->client_version_string) free(p->client_version_string); if (p->server_version_string) free(p->server_version_string); if (p->disc_reason) free(p->disc_reason); }