Cap

Reconnaissance

First we want to run a initial nmap scan to see what ports are open and what services are on those ports.

nmap -sC -sV -oA nmap/init 10.129.141.123

  • -sC: run default nmap scripts

  • -sV: detect service version

  • -oA: output all formats to nmap/initial

We get back the following information:

  • Port 21: running vsftpd version 3.0.3

  • Port 22: running OpenSSH version 8.2p1 Ubuntu 4ubuntu0.2

  • Port 80: running gunicorn web server

init.nmap
# Nmap 7.92 scan initiated Tue Mar 22 18:25:26 2022 as: nmap -sC -sV -oA nmap/init 10.129.141.123
Nmap scan report for 10.129.141.123
Host is up (0.039s latency).
Not shown: 997 closed tcp ports (reset)
PORT   STATE SERVICE VERSION
21/tcp open  ftp     vsftpd 3.0.3
22/tcp open  ssh     OpenSSH 8.2p1 Ubuntu 4ubuntu0.2 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   3072 fa:80:a9:b2:ca:3b:88:69:a4:28:9e:39:0d:27:d5:75 (RSA)
|   256 96:d8:f8:e3:e8:f7:71:36:c5:49:d5:9d:b6:a4:c9:0c (ECDSA)
|_  256 3f:d0:ff:91:eb:3b:f6:e1:9f:2e:8d:de:b3:de:b2:18 (ED25519)
80/tcp open  http    gunicorn
| fingerprint-strings: 
|   FourOhFourRequest: 
|     HTTP/1.0 404 NOT FOUND
|     Server: gunicorn
|     Date: Tue, 22 Mar 2022 22:25:38 GMT
|     Connection: close
|     Content-Type: text/html; charset=utf-8
|     Content-Length: 232
|     <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|     <title>404 Not Found</title>
|     <h1>Not Found</h1>
|     <p>The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again.</p>
|   GetRequest: 
|     HTTP/1.0 200 OK
|     Server: gunicorn
|     Date: Tue, 22 Mar 2022 22:25:33 GMT
|     Connection: close
|     Content-Type: text/html; charset=utf-8
|     Content-Length: 19386
|     <!DOCTYPE html>
|     <html class="no-js" lang="en">
|     <head>
|     <meta charset="utf-8">
|     <meta http-equiv="x-ua-compatible" content="ie=edge">
|     <title>Security Dashboard</title>
|     <meta name="viewport" content="width=device-width, initial-scale=1">
|     <link rel="shortcut icon" type="image/png" href="/static/images/icon/favicon.ico">
|     <link rel="stylesheet" href="/static/css/bootstrap.min.css">
|     <link rel="stylesheet" href="/static/css/font-awesome.min.css">
|     <link rel="stylesheet" href="/static/css/themify-icons.css">
|     <link rel="stylesheet" href="/static/css/metisMenu.css">
|     <link rel="stylesheet" href="/static/css/owl.carousel.min.css">
|     <link rel="stylesheet" href="/static/css/slicknav.min.css">
|     <!-- amchar
|   HTTPOptions: 
|     HTTP/1.0 200 OK
|     Server: gunicorn
|     Date: Tue, 22 Mar 2022 22:25:33 GMT
|     Connection: close
|     Content-Type: text/html; charset=utf-8
|     Allow: GET, OPTIONS, HEAD
|     Content-Length: 0
|   RTSPRequest: 
|     HTTP/1.1 400 Bad Request
|     Connection: close
|     Content-Type: text/html
|     Content-Length: 196
|     <html>
|     <head>
|     <title>Bad Request</title>
|     </head>
|     <body>
|     <h1><p>Bad Request</p></h1>
|     Invalid HTTP Version &#x27;Invalid HTTP Version: &#x27;RTSP/1.0&#x27;&#x27;
|     </body>
|_    </html>
|_http-title: Security Dashboard
|_http-server-header: gunicorn
1 service unrecognized despite returning data. If you know the service/version, please submit the following fingerprint at https://nmap.org/cgi-bin/submit.cgi?new-service :
SF-Port80-TCP:V=7.92%I=7%D=3/22%Time=623A4CDD%P=x86_64-pc-linux-gnu%r(GetR
SF:equest,1480,"HTTP/1\.0\x20200\x20OK\r\nServer:\x20gunicorn\r\nDate:\x20
SF:Tue,\x2022\x20Mar\x202022\x2022:25:33\x20GMT\r\nConnection:\x20close\r\
SF:nContent-Type:\x20text/html;\x20charset=utf-8\r\nContent-Length:\x20193
SF:86\r\n\r\n<!DOCTYPE\x20html>\n<html\x20class=\"no-js\"\x20lang=\"en\">\
SF:n\n<head>\n\x20\x20\x20\x20<meta\x20charset=\"utf-8\">\n\x20\x20\x20\x2
SF:0<meta\x20http-equiv=\"x-ua-compatible\"\x20content=\"ie=edge\">\n\x20\
SF:x20\x20\x20<title>Security\x20Dashboard</title>\n\x20\x20\x20\x20<meta\
SF:x20name=\"viewport\"\x20content=\"width=device-width,\x20initial-scale=
SF:1\">\n\x20\x20\x20\x20<link\x20rel=\"shortcut\x20icon\"\x20type=\"image
SF:/png\"\x20href=\"/static/images/icon/favicon\.ico\">\n\x20\x20\x20\x20<
SF:link\x20rel=\"stylesheet\"\x20href=\"/static/css/bootstrap\.min\.css\">
SF:\n\x20\x20\x20\x20<link\x20rel=\"stylesheet\"\x20href=\"/static/css/fon
SF:t-awesome\.min\.css\">\n\x20\x20\x20\x20<link\x20rel=\"stylesheet\"\x20
SF:href=\"/static/css/themify-icons\.css\">\n\x20\x20\x20\x20<link\x20rel=
SF:\"stylesheet\"\x20href=\"/static/css/metisMenu\.css\">\n\x20\x20\x20\x2
SF:0<link\x20rel=\"stylesheet\"\x20href=\"/static/css/owl\.carousel\.min\.
SF:css\">\n\x20\x20\x20\x20<link\x20rel=\"stylesheet\"\x20href=\"/static/c
SF:ss/slicknav\.min\.css\">\n\x20\x20\x20\x20<!--\x20amchar")%r(HTTPOption
SF:s,B3,"HTTP/1\.0\x20200\x20OK\r\nServer:\x20gunicorn\r\nDate:\x20Tue,\x2
SF:022\x20Mar\x202022\x2022:25:33\x20GMT\r\nConnection:\x20close\r\nConten
SF:t-Type:\x20text/html;\x20charset=utf-8\r\nAllow:\x20GET,\x20OPTIONS,\x2
SF:0HEAD\r\nContent-Length:\x200\r\n\r\n")%r(RTSPRequest,121,"HTTP/1\.1\x2
SF:0400\x20Bad\x20Request\r\nConnection:\x20close\r\nContent-Type:\x20text
SF:/html\r\nContent-Length:\x20196\r\n\r\n<html>\n\x20\x20<head>\n\x20\x20
SF:\x20\x20<title>Bad\x20Request</title>\n\x20\x20</head>\n\x20\x20<body>\
SF:n\x20\x20\x20\x20<h1><p>Bad\x20Request</p></h1>\n\x20\x20\x20\x20Invali
SF:d\x20HTTP\x20Version\x20&#x27;Invalid\x20HTTP\x20Version:\x20&#x27;RTSP
SF:/1\.0&#x27;&#x27;\n\x20\x20</body>\n</html>\n")%r(FourOhFourRequest,189
SF:,"HTTP/1\.0\x20404\x20NOT\x20FOUND\r\nServer:\x20gunicorn\r\nDate:\x20T
SF:ue,\x2022\x20Mar\x202022\x2022:25:38\x20GMT\r\nConnection:\x20close\r\n
SF:Content-Type:\x20text/html;\x20charset=utf-8\r\nContent-Length:\x20232\
SF:r\n\r\n<!DOCTYPE\x20HTML\x20PUBLIC\x20\"-//W3C//DTD\x20HTML\x203\.2\x20
SF:Final//EN\">\n<title>404\x20Not\x20Found</title>\n<h1>Not\x20Found</h1>
SF:\n<p>The\x20requested\x20URL\x20was\x20not\x20found\x20on\x20the\x20ser
SF:ver\.\x20If\x20you\x20entered\x20the\x20URL\x20manually\x20please\x20ch
SF:eck\x20your\x20spelling\x20and\x20try\x20again\.</p>\n");
Service Info: OSs: Unix, Linux; CPE: cpe:/o:linux:linux_kernel

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
# Nmap done at Tue Mar 22 18:27:36 2022 -- 1 IP address (1 host up) scanned in 130.52 seconds

Enumeration

Checking out the webserver I see that I am logged in as the user Nathan

It also appears that I can see netstat information from the server this is running on

The IP Config page shows that I am in fact looking at the box I just enumerated and this is not output from another server

Looking at the security snapshots page I notice something interesting in the address bar

Setting the data value from 1 to 0 I get non-zero values for the number of packets

Opening up the pcap that is downloaded in wireshark I almost immediately spot a username and password

Credentials

Username: nathan Password: Buck3tH4TF0RM3!

Initial Access

These credentials worked for ssh

I am unable to run sudo as the user nathan on the box so I am going to transfer over linpeas using updog

Running linpeas.sh I notice python3.8 has capabilities for setuid

Exploitation

Going to gtfobins I can see we have an easy way to root wth python

Using this command I was able to get root

Lessons Learned

  1. Never allow binaries that can run another binary to have the linux CAP_SETUID capability set as it can be used to escalate privileges and maintain persistence

  2. SSH Should require more than just a password for login

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