LightDM up to 1.22.0 on Ubuntu AppArmor access control

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.
4.3	$0-$5k	0.00

Summaryinfo

A vulnerability classified as critical has been found in LightDM up to 1.22.0 on Ubuntu. This vulnerability affects unknown code of the component AppArmor. The manipulation leads to access control. This vulnerability is listed as CVE-2017-8900. It is possible to launch the attack on the physical device. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in LightDM up to 1.22.0 on Ubuntu and classified as critical. This issue affects some unknown processing of the component AppArmor. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

LightDM through 1.22.0, when systemd is used in Ubuntu 16.10 and 17.x, allows physically proximate attackers to bypass intended AppArmor restrictions and visit the home directories of arbitrary users by establishing a guest session.

The bug was discovered 05/11/2017. The weakness was presented 05/12/2017 (Website). The advisory is shared at launchpad.net. The identification of this vulnerability is CVE-2017-8900 since 05/11/2017. An attack has to be approached locally. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1068 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 100156 (Ubuntu 16.10 / 17.04 : lightdm vulnerability (USN-3285-1)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Ubuntu Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 276926 (Fedora Security Update for lightdm (FEDORA-2017-d793fef58f)).

Upgrading eliminates this vulnerability. A possible mitigation has been published even before and not after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (100156) and SecurityFocus (BID 98554†). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Name

• LightDM

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22.0

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.3

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 4.6
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

NVD Base Score: 🔍

Exploitinginfo

Class: Access control
CWE: CWE-284 / CWE-266
CAPEC: 🔍
ATT&CK: 🔍

Physical: Yes
Local: Yes
Remote: No

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 100156
Nessus Name: Ubuntu 16.10 / 17.04 : lightdm vulnerability (USN-3285-1)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 841810
OpenVAS Name: Ubuntu Update for lightdm USN-3285-1
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Timelineinfo

02/09/2017 🔍
05/11/2017 +91 days 🔍
05/11/2017 +0 days 🔍
05/11/2017 +0 days 🔍
05/12/2017 +1 days 🔍
05/12/2017 +0 days 🔍
05/12/2017 +0 days 🔍
05/12/2017 +0 days 🔍
12/06/2022 +2034 days 🔍

Sourcesinfo

Advisory: usn-3285-1
Researcher: Tyler Hicks
Status: Not defined
Confirmation: 🔍

CVE: CVE-2017-8900 (🔍)
GCVE (CVE): GCVE-0-2017-8900
GCVE (VulDB): GCVE-100-101093
SecurityFocus: 98554 - LightDM CVE-2017-8900 Local Security Bypass Vulnerability
OSVDB: - CVE-2017-8900 - LightDM - Security Bypass Issue

Entryinfo

Created: 05/12/2017 14:38
Updated: 12/06/2022 10:46
Changes: 05/12/2017 14:38 (70), 09/25/2020 14:12 (7), 12/23/2020 09:43 (2), 12/06/2022 10:46 (3)
Complete: 🔍
Cache ID: 216::103

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