Perform NetBSD security audit with pkg_admin
Perform NetBSD security audit
Security audit of NetBSD software packages with pkg_admin
NetBSD is especially known for it’s diverse platforms it can run on. What is less known is the ability to audit the installed packages. In this article we have a look on how to audit NetBSD and ensure the file integrity of your packages. Performing a security audit is easy, as long as you use the right tool!
When using packages, their metadata will be installed in directory within /var/db/pkg. This tree contains information about the packages.
netbsd# cd /var/db/pkg netbsd# ls -l total 146 drwxr-xr-x 2 root wheel 512 Dec 3 17:23 atf-0.20 drwxr-xr-x 2 root wheel 512 Nov 24 2013 libidn-1.28 -rw-r--r-- 1 root wheel 106391 Dec 3 17:07 pkg-vulnerabilities drwxr-xr-x 2 root wheel 512 Nov 24 2013 pkg_install-20130902 -rw-r--r-- 1 root wheel 28672 Dec 3 17:23 pkgdb.byfile.db drwxr-xr-x 2 root wheel 512 Nov 24 2013 pkgin-0.6.4nb1 drwxr-xr-x 2 root wheel 512 Dec 3 17:23 shtk-1.4 drwxr-xr-x 2 root wheel 512 Dec 3 17:23 sysupgrade-1.5nb1 drwxr-xr-x 2 root wheel 512 Dec 3 17:13 wget-1.14nb3
This directory can also contain a file named pkg-vulnerabilities. This file contains information about software vulnerabilities and can be used to check what installed software packages are vulnerable.
When we look into the subdirectories within /var/db/pkgs, we see a structured format of files, which include the actual metadata about the package.
# ls -l total 78 -r--r--r-- 1 root wheel 3455 Nov 24 2013 +BUILD_INFO -r--r--r-- 1 root wheel 398 Nov 24 2013 +BUILD_VERSION -r--r--r-- 1 root wheel 46 Nov 24 2013 +COMMENT -rw-r--r-- 1 root wheel 3784 Nov 24 2013 +CONTENTS -r-xr-xr-x 1 root wheel 4075 Nov 24 2013 +DEINSTALL -r--r--r-- 1 root wheel 530 Nov 24 2013 +DESC -rwxr-xr-x 1 root wheel 9090 Nov 24 2013 +DIRS -rwxr-xr-x 1 root wheel 11075 Nov 24 2013 +FILES -rwxr-xr-x 1 root wheel 2838 Nov 24 2013 +INFO_FILES -r-xr-xr-x 1 root wheel 28793 Nov 24 2013 +INSTALL -r--r--r-- 1 root wheel 8 Nov 24 2013 +SIZE_ALL -r--r--r-- 1 root wheel 8 Nov 24 2013 +SIZE_PKG
Besides normal information (like a version number), there are actually some shell scripts. Mostly they deal with the directories, files and permissions.
Install pkg-vulnerabilities file
Before checking the system, it will need the pkg-vulnerabilities file. Installing is as easy as running the pkg_admin tool with the fetch-pkg-vulnerabilities parameter.
# pkg_admin fetch-pkg-vulnerabilities
Checking the integrity of the vulnerabilities file
The pkg_admin tool is also able to check the integrity of the fetched file. Normally it should show no output, meaning everything is fine. If not, something like this shows up:
# pkg_admin check-pkg-vulnerabilities /var/db/pkg/pkg-vulnerabilities pkg_admin: SHA1 hash doesn't match
Running vulnerability scan
With the audit parameter we can start a vulnerability scan. It perform a security audit on the installed packages. Every package which matches a specific version, will be flagged.
Another thing the pkg_admin tool can perform, is an integrity check of the installed files. It uses the metadata from the packages directory and compares them with the actual files on disk.
This small NetBSD utility is very nifty tool and a sign that NetBSD is taking security serious as well. Happy auditing!