Linux Kernel up to 4.19.1 Access Control kernel/user_namespace.c map_write input validation

CVSS Meta Temp Score
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CTI Interest Score
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5.6$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 4.19.1. Affected by this issue is the function map_write of the file kernel/user_namespace.c of the component Access Control. Performing a manipulation results in input validation. This vulnerability was named CVE-2018-18955. The attack needs to be approached locally. In addition, an exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 4.19.1 (Operating System). This affects the function map_write of the file kernel/user_namespace.c of the component Access Control. The manipulation with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel 4.15.x through 4.19.x before 4.19.2, map_write() in kernel/user_namespace.c allows privilege escalation because it mishandles nested user namespaces with more than 5 UID or GID ranges. A user who has CAP_SYS_ADMIN in an affected user namespace can bypass access controls on resources outside the namespace, as demonstrated by reading /etc/shadow. This occurs because an ID transformation takes place properly for the namespaced-to-kernel direction but not for the kernel-to-namespaced direction.

The bug was discovered 11/05/2018. The weakness was presented 11/16/2018 by Jann Horn (Website). It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2018-18955 since 11/05/2018. Attacking locally is a requirement. No form of authentication is needed for exploitation. Technical details and a public exploit are known.

The exploit is shared for download at exploit-db.com. It is declared as highly functional. The vulnerability was handled as a non-public zero-day exploit for at least 11 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 119302 (Ubuntu 18.10 : linux-aws vulnerabilities (USN-3832-1)), 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 197316 (Ubuntu Security Notification for Linux-aws Vulnerabilities (USN-3832-1)).

Upgrading eliminates this vulnerability. A possible mitigation has been published 2 weeks after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Exploit-DB (45886), Tenable (119302) and SecurityFocus (BID 105941†). See VDB-125740, VDB-125976 and VDB-126010 for similar entries. Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

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CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.7
VulDB Meta Temp Score: 5.6

VulDB Base Score: 4.5
VulDB Temp Score: 4.3
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.0
NVD Vector: 🔍

CVSSv2info

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VulDB Base Score: 🔍
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Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: No

Availability: 🔍
Access: Public
Status: Highly functional
Download: 🔍

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Price Prediction: 🔍
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Nessus ID: 119302
Nessus Name: Ubuntu 18.10 : linux-aws vulnerabilities (USN-3832-1)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

MetaSploit ID: nested_namespace_idmap_limit_priv_esc.rb
MetaSploit Name: Linux Nested User Namespace idmap Limit Local Privilege Escalation
MetaSploit File: 🔍

Exploit-DB: 🔍

Threat Intelligenceinfo

Interest: 🔍
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Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
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Patch: git.kernel.org

Timelineinfo

11/05/2018 🔍
11/05/2018 +0 days 🔍
11/16/2018 +11 days 🔍
11/16/2018 +0 days 🔍
11/16/2018 +0 days 🔍
11/17/2018 +1 days 🔍
11/30/2018 +13 days 🔍
11/30/2018 +0 days 🔍
06/23/2024 +2032 days 🔍

Sourcesinfo

Vendor: kernel.org

Advisory: K39103040
Researcher: Jann Horn
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2018-18955 (🔍)
GCVE (CVE): GCVE-0-2018-18955
GCVE (VulDB): GCVE-100-126963
SecurityFocus: 105941 - Linux Kernel CVE-2018-18955 Local Privilege Escalation Vulnerability

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

Entryinfo

Created: 11/17/2018 11:25
Updated: 06/23/2024 20:28
Changes: 11/17/2018 11:25 (80), 04/13/2020 19:01 (10), 06/06/2023 17:54 (5), 06/06/2023 18:02 (1), 06/23/2024 20:28 (14)
Complete: 🔍
Cache ID: 216::103

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