abraxaslabs.tech  ·  github.com/abraxas  ·  @abraxas_null  ·  [email protected]  ·  pfsense-igmp-type

pfsense-igmp-type

Class: Config injection Reach: Remote

pfSense CE 2.9.0-DEVELOPMENT (9363ac5) - pfsense.org

services_igmpproxy_edit.php stores POST type with no enum check. configure interpolates phyint {$realif} {$igmpcf['type']} ... into igmpproxy.conf.

ID	no CVE yet
Class	Config injection
Reach	Remote (authenticated WebGUI unless noted)
CWE	CWE-74
CVSS	Medium: 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
Product	pfSense CE
Affected	2.9.0-DEVELOPMENT (9363ac5b8651a1c7a333180425ce7719070f95f9)
Auth	WebGUI session with page-services-igmpproxy-edit
License	GNU Affero GPL v3.0
Lab	127.0.0.1 only

I pinned public master 9363ac5. The lab is a PHP gadget of the pinned sink, loopback HTTP on 127.0.0.1:19240.

Series write-up: https://abraxaslabs.tech/research/pfsense-ce-leftovers

What an attacker can do

Method	Sink	Privilege
POST services_igmpproxy_edit.php type	phyint {$realif} {$igmpcf['type']} ...	Integrity: Lab-proven: extra conf line. Daemon argv unchanged. Not shell.
same leftover	same sink	Recon: None shown.
same leftover	same sink	Availability: Inferred: parse-fail igmpproxy.

Requires: page-services-igmpproxy-edit. CSRF-magic on POST unless noted. WebGUI PHP-FPM is root.

Requires: page-services-igmpproxy-edit. CSRF-magic on POST unless noted. WebGUI PHP-FPM is root. CSRF-magic on POST unless noted. WebGUI PHP-FPM is root.

Adjacent surface that stays closed

ifname needs an IPv4 ipaddr. threshold is_numeric. addresses is_subnetv4.

No Diagnostics: Command unless that page is also granted.

Lab

cd lab
./run.sh

Loopback 127.0.0.1:19240. Compose project pfsense-igmp-type. Witness PFSENSE-IGMP-TYPE-WITNESS. Loopback only: 127.0.0.1:19240. Compose project pfsense-igmp-type. Witness PFSENSE-IGMP-TYPE-WITNESS. PHP gadget of the pinned lines. Stack tears down after the run.

Last line:

SUCCESS PFSENSE-IGMP-TYPE control-type-upstream=yes trigger-extra-conf=yes PFSENSE-IGMP-TYPE-WITNESS

Fix

Enum type to upstream/downstream. Reject CR/LF.

References

• github.com/pfsense/pfsense 9363ac5b8651a1c7a333180425ce7719070f95f9
• CWE-74
• Series: https://abraxaslabs.tech/research/pfsense-ce-leftovers