CVE-2015-3636

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ModerateModerate ImpactWhat does this mean?
DescriptionStatementMitigationAdditional informationAffected PackagesCVSS Score DetailsWeakness (CWE)FAQ

Description

It was found that the Linux kernel's ping socket implementation did not properly handle socket unhashing during spurious disconnects, which could lead to a use-after-free flaw. On x86-64 architecture systems, a local user able to create ping sockets could use this flaw to crash the system. On non-x86-64 architecture systems, a local user able to create ping sockets could use this flaw to escalate their privileges on the system.

It was found that the Linux kernel's ping socket implementation did not properly handle socket unhashing during spurious disconnects, which could lead to a use-after-free flaw. On x86-64 architecture systems, a local user able to create ping sockets could use this flaw to crash the system. On non-x86-64 architecture systems, a local user able to create ping sockets could use this flaw to escalate their privileges on the system.

Statement

This issue does not affect the Linux kernel as shipped with Red Hat Enterprise Linux 5. This issue does affect the Linux kernel as shipped with Red Hat Enterprise Linux 6, 7 and Red Hat Enterprise MRG 2. Future kernel updates for the respective releases will address this issue. Please note that on x86-64 architecture systems the impact is limited to local Denial of Service and that the ping sockets functionality is disabled by default (net.ipv4.ping_group_range sysctl is "1 0").

This issue does not affect the Linux kernel as shipped with Red Hat Enterprise Linux 5. This issue does affect the Linux kernel as shipped with Red Hat Enterprise Linux 6, 7 and Red Hat Enterprise MRG 2. Future kernel updates for the respective releases will address this issue.

Please note that on x86-64 architecture systems the impact is limited to local Denial of Service and that the ping sockets functionality is disabled by default (net.ipv4.ping_group_range sysctl is "1 0").

Mitigation

You can check whether ping socket functionality is enabled by examining the net.ipv4.ping_group_range sysctl value:

~]# sysctl net.ipv4.ping_group_range
net.ipv4.ping_group_range = 1 0

"1 0" is the default value and disables the ping socket functionality even for root user. Any other value means that the ping socket functionality might be enabled for certain users on the system.

To mitigate this vulnerability make sure that you either allow the functionality to trusted local users (groups) only or set the net.ipv4.ping_group_range sysctl to the default and disabled state:

~]# sysctl net.ipv4.ping_group_range="1 0"

Please note that this might prevent some programs relying on this functionality from functioning properly.

Additional information

  • Bugzilla 1218074: kernel: ping sockets: use-after-free leading to local privilege escalation
  • CWE-416: Use After Free
  • FAQ: Frequently asked questions about CVE-2015-3636

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

CVSS v2 Score Breakdown
Red HatNVD

CVSS v2 Base Score

6

4.9

Attack Vector

Local

Local

Access Complexity

High

Low

Authentication

Single

None

Confidentiality Impact

Complete

None

Integrity Impact

Complete

None

Availability Impact

Complete

Complete

CVSS v2 Vector

Red Hat: AV:L/AC:H/Au:S/C:C/I:C/A:C

NVD: AV:L/AC:L/Au:N/C:N/I:N/A:C

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • The term "Affected" means that our Analysis team has determined that this product, such as Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to address this issue in the near future. This includes all minor releases of this product unless noted otherwise in the Statement text.

What can I do if my product is listed as "Will not fix"?

A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our Red Hat Vulnerability Scanner Certification program.

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