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FreeBSD Asmon/Ascpu Vulnerability
FreeBSD - Asmon/Ascpu Vulnerability Privacy and Legal Notice


K-022: FreeBSD - Asmon/Ascpu Vulnerability

February 24, 2000 18:00 GMT
PROBLEM:       Vulnerabilities have been identified in two Afterstep
               utilities, asmon and ascpu, which are distributed with FreeBSD.
               These utilities can allow a malicious user to execute arbitrary
               commands which may allow them elevated privileges.
PLATFORM:      The FreeBSD ports collection before 1/29/2000.
DAMAGE:        Exploiting these vulnerabilities may lead to a root compromise.
SOLUTION:      Either remove the software from the system or upgrade the
               utilities following the information in the attached bulletin.

VULNERABILITY The risk is low. The utilities are part of a third-party port ASSESSMENT: distribution and are not installed by default with FreeBSD.
[****** Begin FreeBSD Security Advisory ******] ============================================================================= FreeBSD-SA-00:03 Security Advisory FreeBSD, Inc. Topic: Asmon/Ascpu ports fail to drop privileges Category: ports Module: asmon/ascpu Announced: 2000-02-19 Affects: Ports collection before the correction date. Corrected: 2000-01-29 FreeBSD only: yes I. Background Two optional third-party ports distributed with FreeBSD can be used to execute commands with elevated privileges, specifically setgid kmem privileges. This may lead to a local root compromise. II. Problem Description Asmon and ascpu allow users to execute arbitrary commands as part of a user configuration file. Both applications are Linux-centric as distributed by the vendor and require patching to run under FreeBSD (specifically, using the kvm interface and setgid kmem privileges to obtain system statistics); this patching was the source of the present security problem. This is a similar flaw to one found in the wmmon port, which was corrected on 1999/12/31. Note that neither utility is installed by default, nor are they "part of FreeBSD" as such: they are part of the FreeBSD ports collection, which contains over 3100 third-party applications in a ready-to-install format. FreeBSD makes no claim about the security of these third-party applications, although an effort is underway to provide a security audit of the most security-critical ports. III. Impact If you have not chosen to install the asmon or ascpu ports/packages, then your system is not vulnerable. If you have, then local users can obtain setgid kmem rights, which allows them to manipulate kernel memory, and thereby compromise root. IV. Workaround Remove the asmon and ascpu ports/packages, if you have installed them. V. Solution One of the following: 1) Upgrade your entire ports collection and rebuild the asmon and/or ascpu ports. 2) Reinstall a new package obtained from: ftp://ftp.freebsd.org/pub/FreeBSD/ports/packages/sysutils/asmon-0.60.tgz ftp://ftp.freebsd.org/pub/FreeBSD/ports/packages/sysutils/ascpu-1.8.tgz after the correction date. At the time of advisory release, the asmon package was not available - you may need to use one of the other methods to update the software. 3) download a new port skeleton for the asmon and/or ascpu ports from: http://www.freebsd.org/ports/ and use it to rebuild one or both ports. 4) Use the portcheckout utility to automate option (3) above. The portcheckout port is available in /usr/ports/devel/portcheckout or the package can be obtained from: ftp://ftp.freebsd.org/pub/FreeBSD/ports/packages/devel/portcheckout-2.0.tgz [****** End FreeBSD Security Advisory ******]

CIAC wishes to acknowledge the contributions of FreeBSD, Inc. for the information contained in this bulletin.

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