Net-SNMP is a suite of applications used to implement SNMP v1, SNMP v2c and SNMP v3 using both IPv4 and IPv6.
This software is available in OpenBSD as a port (/usr/ports/net/net-snmp).
By default, when OpenBSD package and ports are used, the snmpd configuration file has weak permissions which allows a local user to retrieve sensitive information.
By default the permissions of the snmpd configuration file in OpenBSD are 0644 instead of 0600:
# cd /usr/ports/net/net-snmp
# make install clean
[...]
# ls -latr /etc/snmp/snmpd.conf
-rw-r--r-- 1 root wheel 6993 Nov 4 09:16 /etc/snmp/snmpd.conf
#
The same problem occurs when the provided package is installed with:
pkg_add http://ftp.spline.de/pub/OpenBSD/5.8/packages/i386/net-snmp-5.7.3p0.tgz:
# ls -latr /etc/snmp/snmpd.conf
-rw-r--r-- 1 root wheel 6993 Nov 4 08:37 /etc/snmp/snmpd.conf
#
The snmpd configuration file is readable by a local user and contains the credentials for read-only and read-write access (for SNMPv1, SNMPv2 and SNMPv3 protocols) and gives a local user unnecessary/dangerous access:
[...]
rocommunity public default -V systemonly
#rocommunity secret 10.0.0.0/16
rouser authOnlyUser
#rwuser authPrivUser priv
[...]
This problem is OpenBSD-specific as the /var/db/pkg/net-snmp-5.7.3p0/+CONTENTS file confirms:
@ts 1438958635
@sample /etc/snmp/snmpd.conf
Futhermore, by default, /usr/local/sbin/snmpd runs as root.
This problem has been fixed in the -STABLE and -CURRENT packages.
This vulnerability was found by Pierre Kim (@PierreKimSec).
https://pierrekim.github.io/advisories/CVE-2015-8100-openbsd-net-snmp.txt
http://openports.se/net/net-snmp
This advisory is licensed under a Creative Commons Attribution Non-Commercial Share-Alike 3.0 License: http://creativecommons.org/licenses/by-nc-sa/3.0/
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## Advisory Information
Title: OpenBSD package 'net-snmp' information disclosure
Advisory URL: https://pierrekim.github.io/advisories/CVE-2015-8100-openbsd-net-snmp.txt
Blog URL: https://pierrekim.github.io/blog/2015-11-12-CVE-2015-8100-OpenBSD-package-net-snmp-information-disclosure.html
Date published: 2015-11-12
Vendors contacted: Stuart Henderson, OpenBSD Package maintainer
Release mode: Released
CVE: CVE-2015-8100
## Product Description
Net-SNMP is a suite of applications used to implement SNMP v1, SNMP v2c and
SNMP v3 using both IPv4 and IPv6.
This software is available in OpenBSD as a port (/usr/ports/net/net-snmp).
## Vulnerabilities Summary
By default, when OpenBSD package and ports are used, the snmpd configuration file
has weak permissions which allows a local user to retrieve sensitive information.
## Details
By default the permissions of the snmpd configuration file in OpenBSD
are 0644 instead of 0600:
# cd /usr/ports/net/net-snmp
# make install clean
[...]
# ls -latr /etc/snmp/snmpd.conf
-rw-r--r-- 1 root wheel 6993 Nov 4 09:16 /etc/snmp/snmpd.conf
#
The same problem occurs when the provided package is installed with
`pkg_add http://ftp.spline.de/pub/OpenBSD/5.8/packages/i386/net-snmp-5.7.3p0.tgz`:
# ls -latr /etc/snmp/snmpd.conf
-rw-r--r-- 1 root wheel 6993 Nov 4 08:37 /etc/snmp/snmpd.conf
#
The snmpd configuration file is readable by a local user and contains the credentials
for read-only and read-write access (for SNMPv1, SNMPv2 and SNMPv3 protocols) and
gives a local user unnecessary/dangerous access:
[...]
rocommunity public default -V systemonly
#rocommunity secret 10.0.0.0/16
rouser authOnlyUser
#rwuser authPrivUser priv
[...]
This problem is OpenBSD-specific as the /var/db/pkg/net-snmp-5.7.3p0/+CONTENTS file confirms:
@ts 1438958635
@sample /etc/snmp/snmpd.conf
Futhermore, by default, `/usr/local/sbin/snmpd` runs as root.
## Vendor Response
This problem has been fixed in the -STABLE and -CURRENT packages.
## Report Timeline
* Nov 04, 2015: Vulnerability found by Pierre Kim.
* Nov 06, 2015: Stuart Henderson is notified of the vulnerability.
* Nov 06, 2015: Stuart Henderson confirms the vulnerability and fixes the package permissions for the sample configuration file in -current and -stable.
* Nov 06, 2015: Stuart Henderson re-activates an option (can be configured with rc.conf.local) to run net-snmp as a separate uid to improve security.
* Nov 10, 2015: OSS-Security is contacted to get a CVE
* Nov 10, 2015: cve-assign@mitre.org assigns CVE-2015-8100
* Nov 12, 2015: A public advisory is sent to security mailing lists.
## Credit
This vulnerability was found by Pierre Kim (@PierreKimSec).
## References
https://pierrekim.github.io/advisories/CVE-2015-8100-openbsd-net-snmp.txt
http://openports.se/net/net-snmp
## Disclaimer
This advisory is licensed under a Creative Commons Attribution Non-Commercial
Share-Alike 3.0 License: http://creativecommons.org/licenses/by-nc-sa/3.0/
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published on 2015-11-12 00:00:00 by Pierre Kim <pierre.kim.sec@gmail.com>