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Gentoo: GLSA-201603-04 Normal: FUSE Environment Variable Threat

gentoo
Calendar Grey March 9, 2016
Dist Gentoo Esm H88
Gentoo Linux advisory GLSA 202109-08 details a vulnerability in the BIND service leading to denial of service attacks.
The fusermount binary in FUSE does not properly clear the environment before invoking mount or umount as root that allows a local user to overwrite arbitrary files

Summary

The fusermount binary calls setuid(geteuid()) to reset the RUID when it invokes /bin/mount so that it can use privileged mount options that are normally restricted if RUID != EUID. FUSE does not properly clear environment variables before invoking mount or umount as root allowing this to be passed to operations using elevated privileges such as LIBMOUNT_MTAB that is used by the mount commands debugging feature.

Topics%20covered

Topics Covered

security advisory gentoo privilege escalation normal fuse

Resolution

All FUSE users should upgrade to the latest version: # emerge --sync # emerge --ask --oneshot --verbose ">=sys-fs/fuse-2.9.4"

References

[ 1 ] CVE-2015-3202 https://www.cve.org/CVERecord?id=CVE-2015-3202

Availability

This GLSA and any updates to it are available for viewing at the Gentoo Security Website: https://security.gentoo.org/glsa/201603-04
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Concerns

Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users' machines is of utmost importance to us. Any security concerns should be addressed to security@gentoo.org or alternatively, you may file a bug at https://bugs.gentoo.org.

Severity: Normal
Title: FUSE: incorrect filtering of environment variables leading to
Date: March 09, 2016
Bugs: #550152
ID: 201603-04

Topics%20covered

Topics Covered

security advisory gentoo privilege escalation normal fuse

Synopsis

The fusermount binary in FUSE does not properly clear the environment before invoking mount or umount as root that allows a local user to overwrite arbitrary files.

Background

FUSE provides an interface for filesystems implemented in userspace.

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Affected Packages

------------------------------------------------------------------- Package / Vulnerable / Unaffected ------------------------------------------------------------------- 1 sys-fs/fuse < 2.9.4 >= 2.9.4

Impact

===== The FUSE vulnerability allows a local, unprivileged user to overwrite arbitrary files on the system.

Workaround

There is no known work around at this time.

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