Detections
Analytics

Xen: Multiple vulnerabilities in libfsimage disk handling (XSA-443)

high Nessus Plugin ID 182971

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Synopsis

The remote Xen hypervisor installation is missing a security update.

Description

libfsimage contains parsing code for several filesystems, most of them based on grub-legacy code. libfsimage is used by pygrub to inspect guest disks.

Pygrub runs as the same user as the toolstack (root in a priviledged domain).

At least one issue has been reported to the Xen Security Team that allows an attacker to trigger a stack buffer overflow in libfsimage. After further analisys the Xen Security Team is no longer confident in the suitability of libfsimage when run against guest controlled input with super user priviledges.

In order to not affect current deployments that rely on pygrub patches are provided in the resolution section of the advisory that allow running pygrub in deprivileged mode.

A guest using pygrub can escalate its privilege to that of the domain construction tools (i.e., normally, to control of the host).

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Apply the appropriate patch according to the vendor advisory.

See Also

https://xenbits.xen.org/xsa/advisory-443.html

Plugin Details

Severity: High

ID: 182971

File Name: xen_server_XSA-443.nasl

Version: 1.5

Type: local

Family: Misc.

Published: 10/12/2023

Updated: 1/15/2024

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.9

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

Vector: CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C

CVSS Score Source: CVE-2023-34325

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

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

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:xen:xen

Required KB Items: installed_sw/Xen Hypervisor, Settings/ParanoidReport

Exploit Ease: No known exploits are available

Patch Publication Date: 10/10/2023

Vulnerability Publication Date: 10/10/2023

Reference Information

CVE: CVE-2023-34325

IAVB: 2023-B-0081-S