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CVE-2020-28374

Published: 12 January 2021

In drivers/target/target_core_xcopy.c in the Linux kernel before 5.10.7, insufficient identifier checking in the LIO SCSI target code can be used by remote attackers to read or write files via directory traversal in an XCOPY request, aka CID-2896c93811e3. For example, an attack can occur over a network if the attacker has access to one iSCSI LUN. The attacker gains control over file access because I/O operations are proxied via an attacker-selected backstore.

From the Ubuntu Security Team

It was discovered that the LIO SCSI target implementation in the Linux kernel performed insufficient identifier checking in certain XCOPY requests. An attacker with access to at least one LUN in a multiple backstore environment could use this to expose sensitive information or modify data.

Notes

AuthorNote
sbeattie
MITIGATION
XCOPY support is enabled by default, but can be disabled via:
echo 0 > /sys/kernel/config/target/core/<backstore>/<name>/attrib/emulate_3pc
or
targetcli /backstores/<backstore>/<name> set attribute emulate_3pc=0
.
This workaround does *not* affect XCOPY requests sent to tcmu-runner
based backstores.

Mitigation

XCOPY support is enabled by default, but can be disabled via:
  echo 0 > /sys/kernel/config/target/core/<backstore>/<name>/attrib/emulate_3pc
or
  targetcli /backstores/<backstore>/<name> set attribute emulate_3pc=0
.
This workaround does *not* affect XCOPY requests sent to tcmu-runner
based backstores.

Priority

High

Cvss 3 Severity Score

8.1

Score breakdown

Status

Package Release Status
linux
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-132.136)
focal
Released (5.4.0-62.70)
groovy
Released (5.8.0-38.43)
trusty
Released (3.13.0-184.235)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
upstream
Released (5.11~rc4)
xenial
Released (4.4.0-200.232)
Patches:
Introduced by

cbf031f425fd0b30ff10ba83b612753189a6bbbf

Fixed by 2896c93811e39d63a4d9b63ccf12a8fbc226e5e4|local-CVE-2020-28374
linux-aws
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1093.99)
focal
Released (5.4.0-1037.39)
groovy
Released (5.8.0-1020.22)
trusty
Released (4.4.0-1085.89)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
upstream
Released (5.11~rc4)
xenial
Released (4.4.0-1121.135)
linux-aws-5.0
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-aws-5.3)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-aws-5.3
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-aws-5.4)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-aws-5.4
Launchpad, Ubuntu, Debian
bionic
Released (5.4.0-1037.39~18.04.1)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-aws-hwe
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Does not exist

groovy Does not exist

trusty Does not exist

xenial
Released (4.15.0-1093.99~16.04.1)
upstream
Released (5.11~rc4)
linux-azure
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-azure-5.3)
focal
Released (5.4.0-1039.41)
groovy
Released (5.8.0-1019.21)
trusty
Released (4.15.0-1106.118~14.04.1)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
xenial
Released (4.15.0-1106.118~16.04.1)
upstream
Released (5.11~rc4)
linux-azure-4.15
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1106.118)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-azure-5.3
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-azure-5.4)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-azure-5.4
Launchpad, Ubuntu, Debian
bionic
Released (5.4.0-1039.41~18.04.1)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-azure-edge
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-azure-5.3)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-dell300x
Launchpad, Ubuntu, Debian
focal Does not exist

groovy Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

trusty Does not exist

bionic
Released (4.15.0-1011.15)
linux-gcp
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-gcp-5.3)
focal
Released (5.4.0-1036.39)
groovy
Released (5.8.0-1019.20)
trusty Does not exist

xenial
Released (4.15.0-1092.105~16.04.1)
upstream
Released (5.11~rc4)
linux-gcp-4.15
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1092.105)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-gcp-5.3
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-gcp-5.4)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-gcp-5.4
Launchpad, Ubuntu, Debian
bionic
Released (5.4.0-1036.39~18.04.1)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-gcp-edge
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-gcp-5.3)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-gke-4.15
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1078.83)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-gke-5.0
Launchpad, Ubuntu, Debian
bionic
Released (5.0.0-1051.53)
focal Does not exist

groovy Does not exist

trusty Does not exist

xenial Does not exist

upstream
Released (5.11~rc4)
linux-gke-5.3
Launchpad, Ubuntu, Debian
bionic
Released (5.3.0-1040.43)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-gke-5.4
Launchpad, Ubuntu, Debian
bionic
Released (5.4.0-1035.37~18.04.1)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-gkeop
Launchpad, Ubuntu, Debian
bionic Does not exist

focal
Released (5.4.0-1009.10)
groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-gkeop-5.4
Launchpad, Ubuntu, Debian
bionic
Released (5.4.0-1009.10~18.04.1)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-hwe
Launchpad, Ubuntu, Debian
bionic
Released (5.3.0-70.66)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial
Released (4.15.0-132.136~16.04.1)
linux-hwe-5.4
Launchpad, Ubuntu, Debian
bionic
Released (5.4.0-62.70~18.04.1)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-hwe-5.8
Launchpad, Ubuntu, Debian
bionic Does not exist

focal
Released (5.8.0-38.43~20.04.1)
groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-hwe-edge
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-hwe-5.4)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Ignored
(superseded by linux-hwe)
linux-kvm
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1084.86)
focal
Released (5.4.0-1032.33)
groovy
Released (5.8.0-1016.18)
trusty Does not exist

upstream
Released (5.11~rc4)
xenial
Released (4.4.0-1087.96)
linux-lts-trusty
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-lts-xenial
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Does not exist

groovy Does not exist

trusty
Released (4.4.0-200.232~14.04.1)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
upstream
Released (5.11~rc4)
xenial Does not exist

linux-oem
Launchpad, Ubuntu, Debian
bionic Ignored
(end of life, was needs-triage)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Ignored
(end of standard support)
linux-oem-5.10
Launchpad, Ubuntu, Debian
bionic Does not exist

focal
Released (5.10.0-1014.15)
groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-oem-5.6
Launchpad, Ubuntu, Debian
bionic Does not exist

focal
Released (5.6.0-1047.51)
groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-oem-osp1
Launchpad, Ubuntu, Debian
bionic Ignored
(end of standard support, was needs-triage)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-oracle
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1064.71)
focal
Released (5.4.0-1037.40)
groovy
Released (5.8.0-1017.18)
trusty Does not exist

upstream
Released (5.11~rc4)
xenial
Released (4.15.0-1064.71~16.04.1)
linux-oracle-5.0
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-oracle-5.3)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-oracle-5.3
Launchpad, Ubuntu, Debian
bionic Ignored
(superseded by linux-oracle-5.4)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-oracle-5.4
Launchpad, Ubuntu, Debian
bionic
Released (5.4.0-1037.40~18.04.1)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-raspi
Launchpad, Ubuntu, Debian
bionic Does not exist

focal
Released (5.4.0-1028.31)
groovy
Released (5.8.0-1013.16)
trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-raspi-5.4
Launchpad, Ubuntu, Debian
bionic
Released (5.4.0-1028.31~18.04.1)
upstream
Released (5.11~rc4)
xenial Does not exist

focal Does not exist

groovy Does not exist

trusty Does not exist

linux-raspi2
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1078.83)
focal Ignored
(replaced by linux-raspi)
groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial
Released (4.4.0-1145.155)
linux-raspi2-5.3
Launchpad, Ubuntu, Debian
bionic
Released (5.3.0-1037.39)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-riscv
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Ignored
(end of life, was needs-triage)
groovy
Released (5.8.0-14.16)
trusty Does not exist

upstream
Released (5.11~rc4)
xenial Does not exist

linux-snapdragon
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1095.104)
focal Does not exist

groovy Does not exist

trusty Does not exist

upstream
Released (5.11~rc4)
xenial
Released (4.4.0-1149.159)

Severity score breakdown

Parameter Value
Base score 8.1
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N