OpenSSH up to 7.2p1 X11 Authentication Credential xauth crlf injection

CVSS Meta Temp Score
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6.0$0-$5k0.00

Summaryinfo

A vulnerability categorized as problematic has been discovered in OpenSSH up to 7.2p1. This affects the function xauth of the component X11 Authentication Credential Handler. Such manipulation leads to crlf injection. This vulnerability is referenced as CVE-2016-3115. It is possible to launch the attack remotely. Furthermore, an exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in OpenSSH up to 7.2p1 (Connectivity Software) and classified as problematic. Affected by this issue is the function xauth of the component X11 Authentication Credential Handler. The manipulation with an unknown input leads to a crlf injection vulnerability. Using CWE to declare the problem leads to CWE-93. The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. Impacted is confidentiality, integrity, and availability.

The bug was discovered 03/10/2016. The weakness was published 03/10/2016 by tintinweb as x11fwd.adv as confirmed advisory (Website). The advisory is shared for download at openssh.com. The public release has been coordinated with the vendor. This vulnerability is handled as CVE-2016-3115 since 03/10/2016. The attack may be launched remotely. The successful exploitation needs a simple authentication. Technical details as well as a public exploit are known. The advisory points out:

Injection of xauth commands grants the ability to read arbitrary files under the authenticated user's privilege, Other xauth commands allow limited information leakage, file overwrite, port probing and generally expose xauth(1), which was not written with a hostile user in mind, as an attack surface.

The exploit is available at exploit-db.com. It is declared as proof-of-concept. The vulnerability was handled as a non-public zero-day exploit for at least 7 days. During that time the estimated underground price was around $25k-$100k. The vulnerability scanner Nessus provides a plugin with the ID 89836 (Slackware 13.0 / 13.1 / 13.37 / 14.0 / 14.1 / current : openssh (SSA:2016-070-01)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Slackware Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 196464 (Ubuntu Security Notification for Openssh Vulnerabilities (USN-2966-1)). The advisory illustrates:

xauth(1) is run under the user's privilege, so this vulnerability offers no additional access to unrestricted accounts, but could circumvent key or account restrictions such as sshd_config ForceCommand, authorized_keys command="..." or restricted shells.

Upgrading to version 7.2p2 eliminates this vulnerability. It is possible to mitigate the problem by applying the configuration setting X11Forwarding=no. The best possible mitigation is suggested to be upgrading to the latest version. A possible mitigation has been published immediately after the disclosure of the vulnerability. The advisory contains the following remark:

OpenSSH 7.2p2 implements a whitelist of characters that are permitted to appear in X11 authentication credentials.

The vulnerability is also documented in the databases at Exploit-DB (39569), Tenable (89836), SecurityFocus (BID 84314†), SecurityTracker (ID 1035249†) and Vulnerability Center (SBV-57239†). Similar entry is available at VDB-80330. VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

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CPE 2.3info

CPE 2.2info

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CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.1

VulDB Base Score: 6.3
VulDB Temp Score: 5.7
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 6.4
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
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NVD Base Score: 🔍

Exploitinginfo

Class: Crlf injection
CWE: CWE-93 / CWE-74 / CWE-707
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Access: Public
Status: Proof-of-Concept
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 89836
Nessus Name: Slackware 13.0 / 13.1 / 13.37 / 14.0 / 14.1 / current : openssh (SSA:2016-070-01)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 80056
OpenVAS Name: Oracle Linux Local Check: ELSA-2016-3531
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Exploit-DB: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

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

Upgrade: OpenSSH 7.2p2
Config: X11Forwarding=no

Timelineinfo

03/03/2016 🔍
03/10/2016 +7 days 🔍
03/10/2016 +0 days 🔍
03/10/2016 +0 days 🔍
03/10/2016 +0 days 🔍
03/10/2016 +0 days 🔍
03/10/2016 +0 days 🔍
03/10/2016 +0 days 🔍
03/11/2016 +1 days 🔍
03/11/2016 +0 days 🔍
03/13/2016 +2 days 🔍
03/22/2016 +9 days 🔍
01/19/2025 +3225 days 🔍

Sourcesinfo

Advisory: x11fwd.adv
Researcher: tintinweb
Status: Confirmed
Confirmation: 🔍
Coordinated: 🔍

CVE: CVE-2016-3115 (🔍)
GCVE (CVE): GCVE-0-2016-3115
GCVE (VulDB): GCVE-100-81320
SecurityFocus: 84314 - OpenSSH CVE-2016-3115 Remote Command Injection Vulnerability
SecurityTracker: 1035249
Vulnerability Center: 57239 - OpenSSH before 7.2p2 Remote Code Execution due to Improper Validation of User Credentials, High

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

Entryinfo

Created: 03/11/2016 09:32
Updated: 01/19/2025 23:29
Changes: 03/11/2016 09:32 (99), 07/20/2019 11:26 (6), 07/10/2022 09:01 (3), 01/19/2025 23:29 (14)
Complete: 🔍
Cache ID: 216:404:103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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