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CVE-2020-28374

Publication date 12 January 2021

Last updated 24 July 2024

Ubuntu priority

High

Why this priority?

Cvss 3 Severity Score

8.1 · High

Score breakdown

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.

Read the notes from the security team

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.

Status

Package Ubuntu Release Status
linux 20.10 groovy
Fixed 5.8.0-38.43
20.04 LTS focal
Fixed 5.4.0-62.70
18.04 LTS bionic
Fixed 4.15.0-132.136
16.04 LTS xenial
Fixed 4.4.0-200.232
14.04 LTS trusty
linux-aws 20.10 groovy
Fixed 5.8.0-1020.22
20.04 LTS focal
Fixed 5.4.0-1037.39
18.04 LTS bionic
Fixed 4.15.0-1093.99
16.04 LTS xenial
Fixed 4.4.0-1121.135
14.04 LTS trusty
linux-aws-5.0 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-5.3 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-5.4 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.4.0-1037.39~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-hwe 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial
Fixed 4.15.0-1093.99~16.04.1
14.04 LTS trusty Not in release
linux-azure 20.10 groovy
Fixed 5.8.0-1019.21
20.04 LTS focal
Fixed 5.4.0-1039.41
18.04 LTS bionic Ignored
16.04 LTS xenial
Fixed 4.15.0-1106.118~16.04.1
14.04 LTS trusty
linux-azure-4.15 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 4.15.0-1106.118
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-5.3 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-5.4 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.4.0-1039.41~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-edge 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-dell300x 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 4.15.0-1011.15
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp 20.10 groovy
Fixed 5.8.0-1019.20
20.04 LTS focal
Fixed 5.4.0-1036.39
18.04 LTS bionic Ignored
16.04 LTS xenial
Fixed 4.15.0-1092.105~16.04.1
14.04 LTS trusty Not in release
linux-gcp-4.15 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 4.15.0-1092.105
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-5.3 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-5.4 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.4.0-1036.39~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-edge 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-4.15 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 4.15.0-1078.83
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-5.0 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.0.0-1051.53
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-5.3 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.3.0-1040.43
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-5.4 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.4.0-1035.37~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gkeop 20.10 groovy Not in release
20.04 LTS focal
Fixed 5.4.0-1009.10
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gkeop-5.4 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.4.0-1009.10~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.3.0-70.66
16.04 LTS xenial
Fixed 4.15.0-132.136~16.04.1
14.04 LTS trusty Not in release
linux-hwe-5.4 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.4.0-62.70~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe-5.8 20.10 groovy Not in release
20.04 LTS focal
Fixed 5.8.0-38.43~20.04.1
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe-edge 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-kvm 20.10 groovy
Fixed 5.8.0-1016.18
20.04 LTS focal
Fixed 5.4.0-1032.33
18.04 LTS bionic
Fixed 4.15.0-1084.86
16.04 LTS xenial
Fixed 4.4.0-1087.96
14.04 LTS trusty Not in release
linux-lts-trusty 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-xenial 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty
linux-oem 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-oem-5.10 20.10 groovy Not in release
20.04 LTS focal
Fixed 5.10.0-1014.15
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oem-5.6 20.10 groovy Not in release
20.04 LTS focal
Fixed 5.6.0-1047.51
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oem-osp1 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle 20.10 groovy
Fixed 5.8.0-1017.18
20.04 LTS focal
Fixed 5.4.0-1037.40
18.04 LTS bionic
Fixed 4.15.0-1064.71
16.04 LTS xenial
Fixed 4.15.0-1064.71~16.04.1
14.04 LTS trusty Not in release
linux-oracle-5.0 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle-5.3 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle-5.4 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.4.0-1037.40~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-raspi 20.10 groovy
Fixed 5.8.0-1013.16
20.04 LTS focal
Fixed 5.4.0-1028.31
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-raspi-5.4 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.4.0-1028.31~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-raspi2 20.10 groovy Not in release
20.04 LTS focal Ignored
18.04 LTS bionic
Fixed 4.15.0-1078.83
16.04 LTS xenial
Fixed 4.4.0-1145.155
14.04 LTS trusty Not in release
linux-raspi2-5.3 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 5.3.0-1037.39
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-riscv 20.10 groovy
Fixed 5.8.0-14.16
20.04 LTS focal Ignored
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-snapdragon 20.10 groovy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Fixed 4.15.0-1095.104
16.04 LTS xenial
Fixed 4.4.0-1149.159
14.04 LTS trusty Not in release

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Notes

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.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
linux

Severity score breakdown

Parameter Value
Base score 8.1 · High
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

References

Related Ubuntu Security Notices (USN)

    • USN-4694-1
    • Linux kernel vulnerability
    • 14 January 2021
    • USN-4709-1
    • Linux kernel vulnerabilities
    • 2 February 2021
    • USN-4711-1
    • Linux kernel vulnerabilities
    • 5 February 2021
    • USN-4713-1
    • Linux kernel vulnerability
    • 2 February 2021
    • USN-4713-2
    • Linux kernel vulnerability
    • 10 February 2021
    • USN-4753-1
    • Linux kernel (OEM) vulnerability
    • 25 February 2021
    • USN-4901-1
    • Linux kernel (Trusty HWE) vulnerabilities
    • 6 April 2021
    • LSN-0074-1
    • Kernel Live Patch Security Notice
    • 26 January 2021

Other references