OpenSSH 7.2p2 Authentication Password Username information disclosure

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.8$0-$5k0.51

A vulnerability classified as problematic has been found in OpenSSH 7.2p2 (Connectivity Software). Affected is an unknown functionality of the component Authentication. The manipulation of the argument Password with an unknown input leads to a information disclosure vulnerability (Username). CWE is classifying the issue as CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. This is going to have an impact on confidentiality.

The weakness was disclosed 07/14/2016 by Eddie Harari as opensshd - user enumeration as confirmed mailinglist post (Full-Disclosure). The advisory is available at seclists.org. The vendor was not involved in the coordination of the public release. This vulnerability is traded as CVE-2016-6210 since 07/13/2016. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details and a public exploit are known. This vulnerability is assigned to T1592 by the MITRE ATT&CK project. The advisory points out:

y 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.

A public exploit has been developed by Eddie Harari in Python and been published immediately after the advisory. The exploit is shared for download at seclists.org. It is declared as highly functional. As 0-day the estimated underground price was around $5k-$25k. The vulnerability scanner Nessus provides a plugin with the ID 92526 (Debian DSA-3626-1 : openssh - security update), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Debian Local Security Checks. The commercial vulnerability scanner Qualys is able to test this issue with plugin 196559 (Ubuntu Security Notification for Openssh Vulnerabilities (USN-3061-1)). The code used by the exploit is:

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)
The advisory illustrates:
Valid users will result in higher total time

Upgrading to version 7.3 eliminates this vulnerability. A possible mitigation has been published 3 weeks after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Exploit-DB (40113), Tenable (92526), SecurityFocus (BID 91812†) and SecurityTracker (ID 1036319†). Further details are available at news.ycombinator.com. The entries VDB-83062 and VDB-90671 are pretty similar. VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 4.8

VulDB Base Score: 5.3
VulDB Temp Score: 4.8
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
unlockunlockunlockunlockunlockunlock
unlockunlockunlockunlockunlockunlock
unlockunlockunlockunlockunlockunlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Name: Username
Class: Information disclosure / Username
CWE: CWE-200 / CWE-284 / CWE-266
CAPEC: 🔍
ATT&CK: 🔍

Local: No
Remote: Yes

Availability: 🔍
Access: Public
Status: Highly functional
Author: Eddie Harari
Programming Language: 🔍
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Dayunlockunlockunlockunlock
Todayunlockunlockunlockunlock

Nessus ID: 92526
Nessus Name: Debian DSA-3626-1 : openssh - security update
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍

OpenVAS ID: 703626
OpenVAS Name: Debian Security Advisory DSA 3626-1 (openssh - security update)
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

MetaSploit ID: ssh_enumusers.rb
MetaSploit Name: SSH Username Enumeration
MetaSploit File: 🔍

Exploit-DB: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍
Exploit Delay Time: 🔍

Upgrade: OpenSSH 7.3

Timelineinfo

07/13/2016 🔍
07/14/2016 +1 days 🔍
07/14/2016 +0 days 🔍
07/16/2016 +2 days 🔍
07/18/2016 +2 days 🔍
08/01/2016 +14 days 🔍
08/01/2016 +0 days 🔍
02/13/2017 +196 days 🔍
09/01/2024 +2757 days 🔍

Sourcesinfo

Advisory: opensshd - user enumeration
Researcher: Eddie Harari
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2016-6210 (🔍)
GCVE (CVE): GCVE-0-2016-6210
GCVE (VulDB): GCVE-100-89622

OVAL: 🔍

SecurityFocus: 91812
SecurityTracker: 1036319 - OpenSSH Lets Remote Users Determine Valid Usernames on the Target System

scip Labs: https://www.scip.ch/en/?labs.20161013
Misc.: 🔍
See also: 🔍

Entryinfo

Created: 07/18/2016 11:46 AM
Updated: 09/01/2024 07:55 PM
Changes: 07/18/2016 11:46 AM (66), 04/19/2017 10:32 AM (27), 09/05/2022 09:52 AM (2), 09/05/2022 09:56 AM (1), 09/01/2024 07:55 PM (14)
Complete: 🔍
Cache ID: 18:855:40

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Might our Artificial Intelligence support you?

Check our Alexa App!