hypervisor stack leak in x86 I/O intercept code

2017-10-1212:00:00

Xen Project

xenbits.xen.org

510

2.1 Low

CVSS2

Attack Vector

LOCAL

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

NONE

Availability Impact

NONE

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

6.5 Medium

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

NONE

Availability Impact

NONE

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

0.001 Low

EPSS

Percentile

26.5%

JSON

ISSUE DESCRIPTION

Intercepted I/O operations may deal with less than a full machine word’s worth of data. While read paths had been the subject of earlier XSAs (and hence have been fixed), at least one write path was found where the data stored into an internal structure could contain bits from an uninitialized hypervisor stack slot. A subsequent emulated read would then be able to retrieve these bits.

IMPACT

A malicious unprivileged x86 HVM guest may be able to obtain sensitive information from the host or other guests.

VULNERABLE SYSTEMS

All Xen versions are vulnerable.
Only x86 systems are affected. ARM systems are not affected.
Only HVM guests can leverage this vulnerability. PV guests cannot leverage this vulnerability.