Executive Summary

Summary
Title Linux kernel IP fragment re-assembly vulnerable to denial of service
Informations
NameVU#641765First vendor Publication2018-08-14
VendorVU-CERTLast vendor Modification2018-10-12
Severity (Vendor) N/ARevisionM

Security-Database Scoring CVSS v2

Cvss vector : (AV:N/AC:L/Au:N/C:N/I:N/A:C)
Cvss Base Score7.8Attack RangeNetwork
Cvss Impact Score6.9Attack ComplexityLow
Cvss Expoit Score10AuthenticationNone Required
Calculate full CVSS 2.0 Vectors scores

Detail

Vulnerability Note VU#641765

Linux kernel IP fragment re-assembly vulnerable to denial of service

Original Release date: 14 Aug 2018 | Last revised: 12 Oct 2018

Overview

The Linux kernel, versions 3.9+, IP implementation is vulnerable to denial of service conditions with low rates of specially modified packets.

Description

CWE-400: Uncontrolled Resource Consumption ('Resource Exhaustion') - CVE-2018-5391

The Linux kernel, versions 3.9+, is vulnerable to a denial of service attack with low rates of specially modified packets targeting IP fragment re-assembly.

An attacker may cause a denial of service condition by sending specially crafted IP fragments.

Various vulnerabilities in IP fragmentation have been discovered and fixed over the years. The current vulnerability (CVE-2018-5391) became exploitable in the Linux kernel with the increase of the IP fragment reassembly queue size.

Impact

An attacker may be able to trigger a denial-of-service condition against the system.

Solution

Apply a patch
Patches are available from OS vendors to address the vulnerability.

If you are unable to apply a patch, see the following mitigations:

Modify Default Configurations
Change the (default) values of net.ipv4/ipv6.ipfrag_high_thresh and net.ipv4/ipv6.ipfrag_low_thresh back to 256kB and 192 kB (respectively) or below.

Example:
sysctl -w net.ipv4.ipfrag_low_thresh=196608
sysctl -w net.ipv4.ipfrag_high_thresh=262144
sysctl -w net.ipv6.ip6frag_low_thresh=196608
sysctl -w net.ipv6.ip6frag_high_thresh=262144


Update:
Further testing shows that these mitigations are not a 100% fix. A significantly strong attack will still result in a denial of service condition.

Revert Commit
Another sufficient mitigation is to revert the commit┬ c2a936600f78aea00d3312ea4b66a79a4619f9b4

Vendor Information (Learn More)

VendorStatusDate NotifiedDate Updated
Arista Networks, Inc.Affected13 Aug 201815 Aug 2018
Check Point Software TechnologiesAffected13 Aug 201813 Sep 2018
Debian GNU/LinuxAffected13 Aug 201815 Aug 2018
MicrosoftAffected13 Aug 201812 Oct 2018
Red Hat, Inc.Affected13 Aug 201815 Aug 2018
SUSE LinuxAffected13 Aug 201812 Sep 2018
UbuntuAffected13 Aug 201815 Aug 2018
BroadcomNot Affected13 Aug 201811 Sep 2018
3com IncUnknown13 Aug 201813 Aug 2018
A10 NetworksUnknown13 Aug 201813 Aug 2018
ACCESSUnknown13 Aug 201813 Aug 2018
Actelis NetworksUnknown13 Aug 201813 Aug 2018
ActiontecUnknown13 Aug 201813 Aug 2018
ADTRANUnknown13 Aug 201813 Aug 2018
aep NETWORKSUnknown13 Aug 201813 Aug 2018
If you are a vendor and your product is affected, let us know.View More »

CVSS Metrics (Learn More)

GroupScoreVector
Base7.8AV:N/AC:L/Au:N/C:N/I:N/A:C
Temporal6.6E:U/RL:ND/RC:ND
Environmental6.6CDP:ND/TD:H/CR:ND/IR:ND/AR:ND

References

  • https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=c30f1fc041b74ecdb072dd44f858750414b8b19f

Credit

Thanks to Juha-Matti Tilli (Aalto University, Department of Communications and Networking / Nokia Bell Labs) for reporting this vulnerability.

This document was written by Trent Novelly.

Other Information

  • CVE IDs:CVE-2018-5391
  • Date Public:14 Aug 2018
  • Date First Published:14 Aug 2018
  • Date Last Updated:12 Oct 2018
  • Document Revision:36

Feedback

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Original Source

Url : http://www.kb.cert.org/vuls/id/641765

CWE : Common Weakness Enumeration

%idName
100 %CWE-20Improper Input Validation

CPE : Common Platform Enumeration

TypeDescriptionCount
Os4
Os2
Os1112
Os2
Os2
Os6
Os4
Os4
Os2

Nessus® Vulnerability Scanner

DateDescription
2018-11-16Name : The remote CentOS host is missing one or more security updates.
File : centos_RHSA-2018-3083.nasl - Type : ACT_GATHER_INFO
2018-10-26Name : The remote EulerOS Virtualization host is missing a security update.
File : EulerOS_SA-2018-1352.nasl - Type : ACT_GATHER_INFO
2018-10-10Name : The remote CentOS host is missing one or more security updates.
File : centos_RHSA-2018-2846.nasl - Type : ACT_GATHER_INFO
2018-09-04Name : The remote EulerOS host is missing multiple security updates.
File : EulerOS_SA-2018-1278.nasl - Type : ACT_GATHER_INFO
2018-09-04Name : The remote EulerOS host is missing multiple security updates.
File : EulerOS_SA-2018-1279.nasl - Type : ACT_GATHER_INFO
2018-08-16Name : The remote Debian host is missing a security update.
File : debian_DLA-1466.nasl - Type : ACT_GATHER_INFO
2018-08-15Name : The remote Amazon Linux 2 host is missing a security update.
File : al2_ALAS-2018-1058.nasl - Type : ACT_GATHER_INFO
2018-08-15Name : The remote Amazon Linux AMI host is missing a security update.
File : ala_ALAS-2018-1058.nasl - Type : ACT_GATHER_INFO
2018-08-15Name : The remote Debian host is missing a security-related update.
File : debian_DSA-4272.nasl - Type : ACT_GATHER_INFO

Alert History

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DateInformations
2018-11-16 21:21:46
  • Multiple Updates
2018-10-12 17:18:37
  • Multiple Updates
2018-10-09 17:18:49
  • Multiple Updates
2018-09-07 00:21:31
  • Multiple Updates
2018-08-31 17:18:57
  • Multiple Updates
2018-08-20 17:18:52
  • Multiple Updates
2018-08-16 21:18:14
  • Multiple Updates
2018-08-15 17:18:52
  • Multiple Updates
2018-08-15 05:17:25
  • First insertion