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FreeBSD Kernel Critical Update: arc4random predictable sequence vulnerability

FreeBSD today released a core (kernel) patched to plug "arc4random predictable sequence vulnerability" security hole in its operating systems version 6.x and 7.x stable release. When the arc4random random number generator is initialized, there may be inadequate entropy to meet the needs of kernel systems which rely on arc4random; and it may take up to 5 minutes before arc4random is reseeded with secure entropy from the Yarrow random number generator. All security-related kernel subsystems that rely on a quality random number generator are subject to a wide range of possible attacks. This update has been rated as having important security impact.

More about arc4random

arc4random(9) is a generic-purpose random number generator based on the key stream generator of the RC4 cipher. It is expected to be cryptographically strong, and used throughout the FreeBSD kernel for a variety of purposes, some of which rely on its cryptographic strength. arc4random(9) is periodically reseeded with entropy from the FreeBSD kernel's Yarrow random number generator, which gathers entropy from a variety of sources including hardware interrupts. During the boot process, additional entropy is provided to the Yarrow random number generator from userland, helping to ensure that adequate entropy is present for cryptographic purposes.


All security-related kernel subsystems that rely on a quality random number generator are subject to a wide range of possible attacks for the 300 seconds after boot or until 64k of random data is consumed.

How do I patch my FreeBSD system?

Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the RELENG_7_0, or RELENG_6_3 security branch using csup command. This will fix the problem.

How to patch current system?

The following patches have been verified to apply to FreeBSD 6.3 and 7.0 systems.

Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility.

Download FreeBSD 7.x patch

# cd /tmp
# fetch http://security.FreeBSD.org/patches/SA-08:11/arc4random.patch
# fetch http://security.FreeBSD.org/patches/SA-08:11/arc4random.patch.asc

Verify patch, enter:
# gpg --verify arc4random.patch.asc arc4random.patch

To apply the patch, enter:
# cd /usr/src
# patch /tmp/arc4random.patch

Download FreeBSD 6.x patch

# cd /tmp
# fetch http://security.FreeBSD.org/patches/SA-08:11/arc4random6x.patch
# fetch http://security.FreeBSD.org/patches/SA-08:11/arc4random6x.patch.asc

Verify patch, enter:
# gpg --verify arc4random6x.patch.asc arc4random6x.patch
To apply the patch, enter:
# cd /usr/src
# patch /tmp/arc4random6x.patch

Recompile your kernel

Now recompile your kernel:
# make kernel KERNCONF=GENERIC
# make installkernel KERNCONF=GENERIC

Replace GENERIC with your actual kernel name. Finally, reboot the system:
# reboot
Make sure everything is working fine, enter:
# uname -a
# tail -f /var/log/messages
# tail -f /path/to/other/log/files
# sockstat

Please see FreeBSD handbook for more information.

Finstall: New GUI installer for FreeBSD Operating System

Finstall is a modern installer for a modern FreeBSD system, with support for advanced features not present in sysinstall:

Finstall: New GUI installer for FreeBSD Operating System

=> More information about project.

FreeBSD Display Information About The System Hardware

FreeBSD comes with different utilities, which can be use to gathered the information as per your needs. uname command is use to print system information. dmesg command is use to print kernel ring buffer information. sysctl command is use to configure kernel parameters at runtime as well as to read hardware information.

Following list summaries, all the command you need to gather FreeBSD hardware information.

1) Determining the Hardware Type/platform:
# uname -m
2) Determining machine processor architecture:
# uname -p
3) Determining FreeBSD release level:
# uname -r
Generally, following command is use to get all info at a time:
# uname -mrs

FreeBSD 5.0-RELEASE i386

4) Determining CPU information such as speed, make etc
# dmesg | grep CPU

CPU: Pentium 4 (1716.41-MHz 686-class CPU)
acpi_cpu0:  on acpi0
acpi_cpu: CPU throttling enabled, 8 steps from 100% to 12.5%

5) Determining real and available memory to FreeBSD:
# dmesg | grep memory

real memory  = 201326592 (192 MB)
avail memory = 188555264 (179 MB) 

Alternatively, try following command to grab memory information:
# sysctl -a | grep hw.*mem
# sysctl -a | grep mem


hw.physmem: 194985984
hw.usermem: 167641088
hw.cbb.start_memory: 2281701376

Note systcl has more info, just type the sysctl command to see rest of all information:
# sysctl -a | less
6) Determining how long a system has been up:
# uptime
7) Determining when a system was last rebooted or shutdown:
# last -1 reboot
# last -1 shutdown

8) Determining swap file system usage
# swapinfo -k
9) Determining who is logged in and what they are doing. Following all commands can be used. users command displays the list of all logged in users only.
# w
# who
# users

10) Find out when user was last logged in - You can use last command as follows:
# last user-name
(a) To find out user vivek was last logged, enter:
# last vivek

See FreeBSD getsysinfo.bash script. It is use to find general FreeBSD system information such as, hostname, OS version, Kernel version, Processor/CPU, Total RAM, System load, network interface, total logged in users, Hard disks, Runlevel etc. Make sure your read the detailed installation instruction.