FreeBSD 11.1/11.2 IP Fragment Reassembly resource consumption

CVSS Meta Temp Score
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CTI Interest Score
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6.3$0-$5k0.00

Summaryinfo

A vulnerability identified as problematic has been detected in FreeBSD 11.1/11.2. This vulnerability affects unknown code of the component IP Fragment Reassembly. Performing a manipulation results in resource consumption. This vulnerability is reported as CVE-2018-6923. The attack is possible to be carried out remotely. No exploit exists. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability was found in FreeBSD 11.1/11.2 (Operating System). It has been classified as problematic. This affects some unknown functionality of the component IP Fragment Reassembly. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability.

The bug was discovered 08/15/2018. The weakness was disclosed 08/14/2018 by Juha-Matti Tilli (ERNE) as FreeBSD-SA-18:10.ip as confirmed security advisory (Website). It is possible to read the advisory at freebsd.org. This vulnerability is uniquely identified as CVE-2018-6923 since 02/12/2018. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK. The advisory points out:

A researcher has notified us of a DoS attack applicable to another operating system. While FreeBSD may not be vulnerable to that exact attack, we have identified several places where inadequate DoS protection could allow an attacker to consume system resources. It is not necessary that the attacker be able to establish two-way communication to carry out these attacks. These attacks impact both IPv4 and IPv6 fragment reassembly.

The vulnerability scanner Nessus provides a plugin with the ID 112070 (FreeBSD : FreeBSD -- Resource exhaustion in IP fragment reassembly (359e1548-a652-11e8-805b-a4badb2f4699)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family FreeBSD Local Security Checks and running in the context l. The advisory illustrates:

In the worst case, an attacker could send a stream of crafted fragments with a low packet rate which would consume a substantial amount of CPU. Other attack vectors allow an attacker to send a stream of crafted fragments which could consume a large amount of CPU or all available mbuf clusters on the system. These attacks could temporarily render a system unreachable through network interfaces or temporarily render a system unresponsive. The effects of the attack should clear within 60 seconds after the attack stops.

Applying the patch r337804/r337828/r337828 is able to eliminate this problem. It is possible to mitigate the problem by applying the configuration setting sysctl net.inet.ip.maxfragpackets=0; sysctl net.inet6.ip6.maxfrags=0. The best possible mitigation is suggested to be patching the affected component. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (112070), SecurityFocus (BID 105336†) and SecurityTracker (ID 1041505†). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔍

CVSSv2info

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

NVD Base Score: 🔍

Exploitinginfo

Class: Resource consumption
CWE: CWE-400 / CWE-404
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 112070
Nessus Name: FreeBSD : FreeBSD -- Resource exhaustion in IP fragment reassembly (359e1548-a652-11e8-805b-a4badb2f4699)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Patch
Status: 🔍

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

Patch: r337804/r337828/r337828
Config: sysctl net.inet.ip.maxfragpackets=0; sysctl net.inet6.ip6.maxfrags=0

Timelineinfo

02/12/2018 🔍
08/14/2018 +182 days 🔍
08/14/2018 +0 days 🔍
08/15/2018 +1 days 🔍
08/16/2018 +0 days 🔍
08/18/2018 +2 days 🔍
08/23/2018 +5 days 🔍
09/04/2018 +11 days 🔍
09/04/2018 +0 days 🔍
05/02/2023 +1701 days 🔍

Sourcesinfo

Product: freebsd.org

Advisory: FreeBSD-SA-18:10.ip
Researcher: Juha-Matti Tilli (ERNE)
Status: Confirmed

CVE: CVE-2018-6923 (🔍)
GCVE (CVE): GCVE-0-2018-6923
GCVE (VulDB): GCVE-100-123027
SecurityFocus: 105336 - FreeBSD TCP Reassembly CVE-2018-6923 Denial Of Service Vulnerability
SecurityTracker: 1041505

Entryinfo

Created: 08/18/2018 13:38
Updated: 05/02/2023 14:36
Changes: 08/18/2018 13:38 (76), 03/16/2020 15:52 (4), 05/02/2023 14:36 (4)
Complete: 🔍
Cache ID: 216::103

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