module

Zyxel chained RCE using LFI and weak password derivation algorithm

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Disclosed
2022-02-01
Created
2023-05-10

Description

This module exploits multiple vulnerabilities in the `zhttpd` binary (/bin/zhttpd)
and `zcmd` binary (/bin/zcmd). It is present on more than 40 Zyxel routers and CPE devices.
The remote code execution vulnerability can be exploited by chaining the local file disclosure
vulnerability in the zhttpd binary that allows an unauthenticated attacker to read the entire configuration
of the router via the vulnerable endpoint `/Export_Log?/data/zcfg_config.json`.
With this information disclosure, the attacker can determine if the router is reachable via ssh
and use the second vulnerability in the `zcmd` binary to derive the `supervisor` password exploiting
a weak implementation of a password derivation algorithm using the device serial number.

After exploitation, an attacker will be able to execute any command as user `supervisor`.

Authors

h00die-gr3y h00die.gr3y@gmail.com
SEC Consult Vulnerability Lab
Thomas Rinsma
Bogi Napoleon Wennerstrøm

Platform

Linux,Unix

Architectures

cmd, mipsbe

References

Module Options

To display the available options, load the module within the Metasploit console and run the commands ‘show options’ or ‘show advanced’:


    msf > use exploit/linux/http/zyxel_lfi_unauth_ssh_rce
    msf exploit(zyxel_lfi_unauth_ssh_rce) > show targets
        ...targets...
    msf exploit(zyxel_lfi_unauth_ssh_rce) > set TARGET < target-id >
    msf exploit(zyxel_lfi_unauth_ssh_rce) > show options
        ...show and set options...
    msf exploit(zyxel_lfi_unauth_ssh_rce) > exploit
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