COMMAND
	    kernel
SYSTEMS AFFECTED
	    FreeBSD/Alpha prior to 2000-05-10 (4.0-STABLE)/2000-04-28 (5.0-CURRENT)
PROBLEM
	    The FreeBSD kernel provides a cryptographic-strength pseudo-random
	    number generator via the /dev/random and /dev/urandom  interfaces,
	    which  samples  hardware  measurements  to  provide a high-quality
	    source of "entropy" (randomness).
	    The  FreeBSD  port  to  the  Alpha  platform  did  not provide the
	    /dev/random or /dev/urandom devices - this was an oversight during
	    the development process which  was not corrected before  the Alpha
	    port "became mainstream".  FreeBSD/i386 is not affected.
	    As a consequence, there is no  way for Alpha systems prior to  the
	    correction date to  obtain cryptographic-strength random  numbers,
	    unless an application "rolls its own" entropy gathering mechanism.
	    This in itself is not a vulnerability, although it is an  omission
	    and a departure from the expected behaviour of a FreeBSD system.
	    The  actual  vulnerability  is  that  some  applications  fail  to
	    correctly check for a working /dev/random and do not exit with  an
	    error if it  is not available,  so this weakness  goes undetected.
	    OpenSSL 0.9.4, and utilities based on it, including OpenSSH  (both
	    of which are included in the base FreeBSD 4.0 system) are affected
	    in  this  manner  (this  bug  was  corrected  in  OpenSSL  0.9.5).
	    Therefore,   cryptographic   security   systems   on    vulnerable
	    FreeBSD/Alpha systems (including OpenSSH  in the base FreeBSD  4.0
	    system)  may  have  weakened  strength,  and  cryptographic   keys
	    generated on such systems should not be trusted.
	    Cryptographic  secrets  (such  as  OpenSSH  public/private   keys)
	    generated on FreeBSD/Alpha systems  may be much weaker  than their
	    "advertised"  strength,  and  may  lead  to  data  compromise to a
	    dedicated and  knowledgeable attacker.   PGP/GnuPG keys,  and keys
	    generated  by  the  SSH  or  SSH2  ports,  are  not believed to be
	    weakened since that software will  correctly detect the lack of  a
	    working  /dev/random  and  use  alternative  sources  of  entropy.
	    OpenSSH  and  OpenSSL  are  currently  the  only  known vulnerable
	    applications.
SOLUTION
	    One of the following three options, followed by step 2).
	    1a) Upgrade your FreeBSD/Alpha system to FreeBSD 4.0-STABLE  after
	        the correction date.
	    1b) install the patched 4.0-RELEASE GENERIC kernel available from:
	
	        ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-00:25/kernel.gz
	
	        e.g. perform the following steps as root:
	
	        # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-00:25/kernel.gz
	        # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-00:25/kernel.gz.asc
	
	      Verify  the  detached  PGP  signature  using  your PGP utility -
	      consult your utility's documentation for how to do this
	
	        # gunzip kernel.gz
	        # cp /kernel /kernel.old
	        # chflags noschg /kernel
	        # cp kernel /kernel
	        # chflags schg /kernel
	
	    1c) Download   the  kernel   source  patch   and  rebuild     your
	        FreeBSD/Alpha kernel, as follows:
	
	        # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-00:25/kernel.sys.diff
	
	        Download the detached PGP signature:
	
	        # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-00:25/kernel.sys.diff.asc
	
	        and verify the signature using your PGP utility.
	        Apply the patch:
	
	        # cd /usr/src
	        # patch -p < /path/to/kernel.sys.diff
	
	        Rebuild your kernel as described in
	
	        http://www.freebsd.org/handbook/kernelconfig.html
	
	        and reboot with the new kernel.
	        NOTE:  Because   of  the   significant  improvements   to  the
	        FreeBSD/Alpha platform in  FreeBSD 4.0, it  is not planned  at
	        this  time  to  backport  the  necessary  changes  to  FreeBSD
	        3.4-STABLE.
	    2) Immediately  regenerate  all  OpenSSH-generated  SSH  keys  and
	       OpenSSL-generated SSL certificates, and any other data  relying
	       on  cryptographic  random  numbers  which  were  generated   on
	       FreeBSD/Alpha  systems,  whose  strength  cannot  be  verified.
	       [Note:  for most systems, the only significant vulnerability is
	       likely  to  be  from  OpenSSH  and  OpenSSL-generated  keys and
	       certificates (e.g. for SSL webservers)]