SB2017081603 - Privilege escalation in Xen

Description

This security bulletin contains information about 5 secuirty vulnerabilities.

1) Privilege escalation (CVE-ID: CVE-2017-12135)

The vulnerability allows a local attacker on the guest system to gain elevated privileges on the host system.

The weakness exists due to flaws in the processing of transitive grants. A local attacker on the guest system can escalate privileges on the host system.

2) Privilege escalation (CVE-ID: CVE-2017-12137)

The vulnerability allows a local attacker on a PV guest system to gain elevated privileges on the host system.

The weakness exists due to a flaw in the processing of guest-nominated L1 pagetable entries when mapping a grant reference. A local attacker on a PV guest system supply specially crafted data and execute arbitrary code on the host system.

3) Privilege escalation (CVE-ID: CVE-2017-12136)

The vulnerability allows a local administrative attacker on the guest system to gain elevated privileges on the host system.

The weakness exists due to a race condition in the grant table allocator maptrack entry list processing code. A local attacker on the guest system can cause the host system to crash or gain elevated privileges on the host system.

4) Privilege escalation (CVE-ID: CVE-2017-12134)

The vulnerability allows a local attacker on a Linux-based guest system to gain elevated privileges on the host system.

The weakness exists due to aa flaw in merging adjacent block IO requests. A local attacker on the guest system can incorrectly access memory during block stream processing to obtain potentially sensitive information or gain elevated privileges on the host system.

5) Privilege escalation (CVE-ID: CVE-2017-12855)

The vulnerability allows a local attacker on the guest system to gain elevated privileges on the host system.

The weakness exists due to flaws when clearing grant status bits. A local attacker on a guest system may modify or reuse a grant that is still in use by another domain and obtain potentially sensitive information from another guest on the target system.


a flaw when clearing grant status bits prematurely. As a result, a guest system may modify or reuse a grant that is still in use by another domain. A local attacker on a guest system may modify or reuse a grant that is still in use by another domain and obtain potentially sensitive information from another guest on the target system.

Remediation

Install update from vendor's website.

References

• http://xenbits.xen.org/xsa/advisory-226.html
• http://xenbits.xen.org/xsa/advisory-227.html
• http://xenbits.xen.org/xsa/advisory-229.html
• http://xenbits.xen.org/xsa/advisory-230.html