Index: channels/chan_sip.c =================================================================== --- channels/chan_sip.c (revision 162867) +++ channels/chan_sip.c (working copy) @@ -6611,10 +6611,81 @@ /*! \brief Send a fake 401 Unauthorized response when the administrator wants to hide the names of local users/peers from fishers */ -static void transmit_fake_auth_response(struct sip_pvt *p, struct sip_request *req, char *randdata, int randlen, int reliable) +static void transmit_fake_auth_response(struct sip_pvt *p, int sipmethod, struct sip_request *req, char *randdata, int randlen, int reliable, int ignore) { - snprintf(randdata, randlen, "%08x", thread_safe_rand()); - transmit_response_with_auth(p, "401 Unauthorized", req, randdata, reliable, "WWW-Authenticate", 0); + /* We have to emulate EXACTLY what we'd get with a good peer + * and a bad password, or else we leak information. */ + char *response = "407 Proxy Authentication Required"; + char *reqheader = "Proxy-Authorization"; + char *respheader = "Proxy-Authenticate"; + const char *authtoken; + + if (sipmethod == SIP_REGISTER || sipmethod == SIP_SUBSCRIBE) { + response = "401 Unauthorized"; + reqheader = "Authorization"; + respheader = "WWW-Authenticate"; + } + + authtoken = get_header(req, reqheader); + if (ignore && !ast_strlen_zero(p->randdata) && ast_strlen_zero(authtoken)) { + /* This is a retransmitted invite/register/etc, don't reconstruct authentication + * information */ + if (!reliable) { + /* Resend message if this was NOT a reliable delivery. Otherwise the + retransmission should get it */ + transmit_response_with_auth(p, response, req, randdata, reliable, respheader, 0); + /* Schedule auto destroy in 15 seconds */ + sip_scheddestroy(p, 15000); + } + } else if (ast_strlen_zero(p->randdata) || ast_strlen_zero(authtoken)) { + /* We have no auth, so issue challenge and request authentication */ + snprintf(p->randdata, sizeof(p->randdata), "%08x", thread_safe_rand()); + transmit_response_with_auth(p, response, req, p->randdata, 0, respheader, 0); + sip_scheddestroy(p, 15000); + } else { + char tmp[256], *c = tmp, *z, *nonce = ""; + + /* Find their response among the mess that we'r sent for comparison */ + ast_copy_string(tmp, authtoken, sizeof(tmp)); + + while (c) { + c = ast_skip_blanks(c); + if (!*c) { + break; + } + if (!strncasecmp(c, "nonce=", strlen("nonce="))) { + c += strlen("nonce="); + if ((*c == '\"')) { + nonce = ++c; + if ((c = strchr(c,'\"'))) { + *c = '\0'; + } + } else { + nonce = c; + if ((c = strchr(c,','))) { + *c = '\0'; + } + } + /* Don't need anything beyond the nonce sent. */ + break; + } else if ((z = strchr(c, ' ')) || (z = strchr(c, ','))) { + c = z; + } + if (c) { + c++; + } + } + /* Verify nonce from request matches our nonce. If not, send 401 with new nonce */ + if (strncasecmp(randdata, nonce, randlen)) { + snprintf(randdata, randlen, "%08x", thread_safe_rand()); + transmit_response_with_auth(p, response, req, randdata, reliable, respheader, 0); + + /* Schedule auto destroy in 15 seconds */ + sip_scheddestroy(p, 15000); + } else { + transmit_response(p, "403 Forbidden (Bad auth)", &p->initreq); + } + } } /*! \brief register_verify: Verify registration of user */ @@ -6736,6 +6807,14 @@ } } } + if (!peer && global_alwaysauthreject) { + /* If we found a peer, we transmit a 100 Trying. Therefore, if we're + * trying to avoid leaking information, we MUST also transmit the same + * response when we DON'T find a peer. */ + transmit_response(p, "100 Trying", req); + /* Insert a fake delay between the 100 and the subsequent failure. */ + sched_yield(); + } if (!res) { ast_device_state_changed("SIP/%s", peer->name); } @@ -6756,7 +6835,7 @@ case -4: /* ACL error */ case -5: /* Peer is not supposed to register with us at all */ if (global_alwaysauthreject) { - transmit_fake_auth_response(p, &p->initreq, p->randdata, sizeof(p->randdata), 1); + transmit_fake_auth_response(p, SIP_REGISTER, &p->initreq, p->randdata, sizeof(p->randdata), 1, ignore); } else { /* URI not found */ if (res == -5) @@ -10699,7 +10778,7 @@ if (res < 0) { if (res == -4) { ast_log(LOG_NOTICE, "Sending fake auth rejection for user %s\n", get_header(req, "From")); - transmit_fake_auth_response(p, req, p->randdata, sizeof(p->randdata), 1); + transmit_fake_auth_response(p, SIP_INVITE, req, p->randdata, sizeof(p->randdata), 1, ignore); } else { ast_log(LOG_NOTICE, "Failed to authenticate user %s\n", get_header(req, "From")); transmit_response_reliable(p, "403 Forbidden", req, 1); @@ -11105,7 +11184,7 @@ if (res < 0) { if (res == -4) { ast_log(LOG_NOTICE, "Sending fake auth rejection for user %s\n", get_header(req, "From")); - transmit_fake_auth_response(p, req, p->randdata, sizeof(p->randdata), 1); + transmit_fake_auth_response(p, SIP_SUBSCRIBE, req, p->randdata, sizeof(p->randdata), 1, ignore); } else { ast_log(LOG_NOTICE, "Failed to authenticate user %s for SUBSCRIBE\n", get_header(req, "From")); if (ignore) Index: channels/chan_iax2.c =================================================================== --- channels/chan_iax2.c (revision 162867) +++ channels/chan_iax2.c (working copy) @@ -164,6 +164,7 @@ static int authdebug = 1; static int autokill = 0; static int iaxcompat = 0; +static int lastauthmethod = 0; static int iaxdefaultdpcache=10 * 60; /* Cache dialplan entries for 10 minutes by default */ @@ -545,6 +546,8 @@ char username[80]; /*! Expected Secret */ char secret[80]; + /*! AUTHREJ all AUTHREP frames */ + int authrej; /*! permitted authentication methods */ int authmethods; /*! permitted encryption methods */ @@ -1444,7 +1447,7 @@ ast_log(LOG_WARNING, "Cannot open '%s': %s\n", s, strerror(errno)); return -1; } - fd = open(s2, O_RDWR | O_CREAT | O_EXCL); + fd = open(s2, O_RDWR | O_CREAT | O_EXCL, 0600); if (fd < 0) { ast_log(LOG_WARNING, "Cannot open '%s' for writing: %s\n", s2, strerror(errno)); close(ifd); @@ -5177,6 +5180,18 @@ if (ast_test_flag(user, IAX_TEMPONLY)) destroy_user(user); res = 0; + } else { + /* user was not found, but we should still fake an AUTHREQ. + * Set authmethods to the last known authmethods used by the system. + * Set a fake secret, it's not looked at, just required to attempt authentication. + * Set authrej so the AUTHREP is rejected without even looking at its contents */ + iaxs[callno]->authmethods = lastauthmethod ? lastauthmethod : (IAX_AUTH_MD5 | IAX_AUTH_PLAINTEXT); + ast_copy_string(iaxs[callno]->secret, "badsecret", sizeof(iaxs[callno]->secret)); + iaxs[callno]->authrej = 1; + if (!ast_strlen_zero(iaxs[callno]->username)) { + /* only send the AUTHREQ if a username was specified. */ + res = 0; + } } ast_set2_flag(iaxs[callno], iax2_getpeertrunk(*sin), IAX_TRUNK); return res; @@ -5276,6 +5291,9 @@ int x; struct iax2_user *user = NULL; + if (p->authrej) { + return res; + } ast_mutex_lock(&userl.lock); user = userl.users; while (user) { @@ -5376,9 +5394,16 @@ ast_log(LOG_NOTICE, "Empty registration from %s\n", ast_inet_ntoa(iabuf, sizeof(iabuf), sin->sin_addr)); return -1; } + + ast_copy_string(iaxs[callno]->peer, peer, sizeof(iaxs[callno]->peer)); + /* Choose lowest expiry number */ + if (expire && (expire < iaxs[callno]->expiry)) + iaxs[callno]->expiry = expire; + /* We release the lock for the call to prevent a deadlock, but it's okay because only the current thread could possibly make it go away or make changes */ ast_mutex_unlock(&iaxsl[callno]); + /* SLD: first call to lookup peer during registration */ p = find_peer(peer, 1); ast_mutex_lock(&iaxsl[callno]); @@ -5386,6 +5411,13 @@ if (!p) { if (authdebug) ast_log(LOG_NOTICE, "No registration for peer '%s' (from %s)\n", peer, ast_inet_ntoa(iabuf, sizeof(iabuf), sin->sin_addr)); + ast_copy_string(iaxs[callno]->secret, "invalidpassword", sizeof(iaxs[callno]->secret)); + + /* A AUTHREQ must be sent to a invalid peer. By returning 0, a REGAUTH with a md5/rsa challenge + * will be sent. If the challenge has already been sent, return -1 to REGREJ the invalid peer. */ + if (ast_strlen_zero(iaxs[callno]->challenge)) { + return 0; + } return -1; } @@ -5419,7 +5451,7 @@ if (key && !ast_check_signature(key, iaxs[callno]->challenge, rsasecret)) { ast_set_flag(&iaxs[callno]->state, IAX_STATE_AUTHENTICATED); break; - } else if (!key) + } else if (!key) ast_log(LOG_WARNING, "requested inkey '%s' does not exist\n", keyn); keyn = strsep(&stringp, ":"); } @@ -5451,7 +5483,7 @@ struct MD5Context md5; unsigned char digest[16]; char *tmppw, *stringp; - + tmppw = ast_strdupa(p->secret); stringp = tmppw; while((tmppw = strsep(&stringp, ";"))) { @@ -5461,7 +5493,7 @@ MD5Final(digest, &md5); for (x=0;x<16;x++) sprintf(requeststr + (x << 1), "%2.2x", digest[x]); /* safe */ - if (!strcasecmp(requeststr, md5secret)) + if (!strcasecmp(requeststr, md5secret)) break; } if (tmppw) { @@ -5473,24 +5505,17 @@ destroy_peer(p); return -1; } - } else if (!ast_strlen_zero(md5secret) || !ast_strlen_zero(secret)) { - if (authdebug) - ast_log(LOG_NOTICE, "Inappropriate authentication received\n"); + } else if (!ast_strlen_zero(iaxs[callno]->challenge) && ast_strlen_zero(md5secret) && ast_strlen_zero(rsasecret)) { + /* if challenge has been sent, but no challenge response if given, reject. */ if (ast_test_flag(p, IAX_TEMPONLY)) destroy_peer(p); return -1; } - ast_copy_string(iaxs[callno]->peer, peer, sizeof(iaxs[callno]->peer)); - /* Choose lowest expiry number */ - if (expire && (expire < iaxs[callno]->expiry)) - iaxs[callno]->expiry = expire; - ast_device_state_changed("IAX2/%s", p->name); /* Activate notification */ if (ast_test_flag(p, IAX_TEMPONLY)) destroy_peer(p); return 0; - } static int authenticate(char *challenge, char *secret, char *keyn, int authmethods, struct iax_ie_data *ied, struct sockaddr_in *sin, aes_encrypt_ctx *ecx, aes_decrypt_ctx *dcx) @@ -6087,23 +6112,33 @@ { struct iax_ie_data ied; struct iax2_peer *p; + int authmethods; + + if (!callno || !iaxs[callno]) { + return 0; + } + /* SLD: third call to find_peer in registration */ - p = find_peer(name, 1); - if (p) { - memset(&ied, 0, sizeof(ied)); - iax_ie_append_short(&ied, IAX_IE_AUTHMETHODS, p->authmethods); - if (p->authmethods & (IAX_AUTH_RSA | IAX_AUTH_MD5)) { - /* Build the challenge */ - snprintf(iaxs[callno]->challenge, sizeof(iaxs[callno]->challenge), "%d", rand()); - iax_ie_append_str(&ied, IAX_IE_CHALLENGE, iaxs[callno]->challenge); - } - iax_ie_append_str(&ied, IAX_IE_USERNAME, name); - if (ast_test_flag(p, IAX_TEMPONLY)) - destroy_peer(p); - return send_command(iaxs[callno], AST_FRAME_IAX, IAX_COMMAND_REGAUTH, 0, ied.buf, ied.pos, -1);; - } - ast_log(LOG_WARNING, "No such peer '%s'\n", name); - return 0; + if ((p = find_peer(name, 1))) { + lastauthmethod = p->authmethods; + } + + authmethods = p ? p->authmethods : lastauthmethod ? lastauthmethod : (IAX_AUTH_PLAINTEXT | IAX_AUTH_MD5); + if (p && ast_test_flag(p, IAX_TEMPONLY)) { + destroy_peer(p); + } else if (!p) { + ast_log(LOG_WARNING, "No such peer '%s'\n", name); + } + + memset(&ied, 0, sizeof(ied)); + iax_ie_append_short(&ied, IAX_IE_AUTHMETHODS, authmethods); + if (authmethods & (IAX_AUTH_RSA | IAX_AUTH_MD5)) { + /* Build the challenge */ + snprintf(iaxs[callno]->challenge, sizeof(iaxs[callno]->challenge), "%d", rand()); + iax_ie_append_str(&ied, IAX_IE_CHALLENGE, iaxs[callno]->challenge); + } + iax_ie_append_str(&ied, IAX_IE_USERNAME, name); + return send_command(iaxs[callno], AST_FRAME_IAX, IAX_COMMAND_REGAUTH, 0, ied.buf, ied.pos, -1);; } static int registry_rerequest(struct iax_ies *ies, int callno, struct sockaddr_in *sin) Index: configs/sip.conf.sample =================================================================== --- configs/sip.conf.sample (revision 162867) +++ configs/sip.conf.sample (working copy) @@ -108,10 +108,12 @@ ; Useful to limit subscriptions to local extensions ; Settable per peer/user also ;notifyringing = yes ; Notify subscriptions on RINGING state -;alwaysauthreject = yes ; When an incoming INVITE or REGISTER is to be rejected, - ; for any reason, always reject with '401 Unauthorized' - ; instead of letting the requester know whether there was - ; a matching user or peer for their request +;alwaysauthreject = yes ; When an incoming INVITE or REGISTER is to be rejected, + ; for any reason, always reject with an identical response + ; equivalent to valid username and invalid password/hash + ; instead of letting the requester know whether there was + ; a matching user or peer for their request. This reduces + ; the ability of an attacker to scan for valid SIP usernames. ; ; If regcontext is specified, Asterisk will dynamically create and destroy a ; NoOp priority 1 extension for a given peer who registers or unregisters with