COMMAND
	    pw suite
	SYTEM AFFECTED
	    FreeBSD
SYSTEMS AFFECTED
PROBLEM
	    The FreeBSD  account administration  pw suite  is able  to produce
	    "random" passwords for new accounts. Due to the simplicity of  the
	    password generation algorithm  involved, the passwords  are easily
	    predictable amid a particular  range of possibilities. This  range
	    may  be  very  narrow,  depending  on  what sort of information is
	    available to the attacker.
	    The  pid  and  the  current  time  in seconds are ored (NOT xored)
	    together and used  as the seed.  Because of this,  the probability
	    of a  lower bit  in the  seed of  being on  is 3/4.  The msb's  of
	    the  seed  change  very  slowly  and  predictably over time and in
	    effect contain no entropy.
	    If the attacker has  access to the file  system then the time  the
	    account  was  created  on  can  by  guessed  very  accurately   by
	    examining the  creation date  of the  new account's  directory, or
	    the creation date of the new account's mail spool file.
	    With  the  time  part  of  the  seed  known it is then possible to
	    generate an  a mask  to eliminate  50% of  the remaining  possible
	    pid values.  The pid  can be  further approximated retrospectively
	    by correlation  between time  stamps and  pid values  from a  wide
	    number of  file system  sources such  as the  pid of  the sendmail
	    task  used  to  deliver  the  new-user  mail, to names of /tmp and
	    queue files.  An active  attack (looking  for the  "pw" process or
	    other  signs  of  account  creation)  will  of  course  locate the
	    pid very closely, if not exactly.
SOLUTION
	    Patch   addresses   the   problem   is   given   by   Julian    A.
	    ([email protected]) who originally described this vulnerability.
	 --- /usr/src/usr.sbin/pw/pw_user.c.orig  Thu  Dec
	12 02:10:47 1996 +++ /usr/src/usr.sbin/pw/pw_user.c  Sat  Dec  14  11:37:50
	1996 @@ -33,6 +33,10 @@
	 #include <sys/param.h>
	 #include <dirent.h>
	 #include <termios.h>
	+#include <sys/types.h> +#include  <sys/time.h>  +#include
	<sys/resource.h> +#include <md5.h>
	 #include "pw.h"
	 #include "bitmap.h"
	 #include "pwupd.h"
	@@ -738,19 +742,61 @@
	        return strcpy(buf, crypt(password, salt));
	 }
	+u_char  *  +pw_genmd5rand   (u_char   *d)   /*   cryptographically   secure
	rng  */  +{  +  MD5_CTX  md5_ctx;  +   struct   timeval   tv,   tvo;   +
	struct  rusage  ru;  +  int  n=0;   +   int   t;   +   MD5Init   (&md5_ctx);
	+  t=getpid();   +   MD5Update   (&md5_ctx,   (u_char*)&t,   sizeof
	t);  +   t=getppid();   +   MD5Update   (&md5_ctx,   (u_char*)&t,
	sizeof   t);   +   gettimeofday   (&tvo,   NULL);   +   do    {    +
	getrusage   (RUSAGE_SELF,   &ru);    +    MD5Update    (&md5_ctx,
	(u_char*)&ru,   sizeof   ru);   +   gettimeofday   (&tv,    NULL);
	+   MD5Update   (&md5_ctx,   (u_char*)&tv,   sizeof    tv);    +
	} while (n++<20 ||  tv.tv_usec-tvo.tv_usec<  100*1000);  +
	MD5Final (d, &md5_ctx); + return d; +}  +  +static  u_char  *  +pw_getrand(u_char
	*buf,   int   len)   +{   +   int   fd;   +    fd    =    open("/dev/urandom",
	O_RDONLY);  +  if  (fd  ==  -1  ||  read(fd,   buf,   len)!=len)   {   +
	int      n;      +      for      (n=0;n<len;n+=16)      {       +
	u_char        ubuf[16];         +         pw_genmd5rand(ubuf);         +
	memcpy(buf+n,    ubuf,    MIN(16,    len-n));    +    }    +     }     +
	close(fd); +       return buf; +}
	 static char    *
	 pw_password(struct userconf * cnf, struct cargs * args, char const * user)
	 {
	        int             i, l;
	        char            pwbuf[32];
	+       u_char          rndbuf[sizeof pwbuf];
	        switch (cnf->default_password) {
	        case -1:                /* Random password */
	                srandom((unsigned) (time(NULL) | getpid()));
	                l = (random() % 8 + 8); /* 8 - 16 chars */
	+               pw_getrand(rndbuf, l);
	                for (i = 0; i<l; i++)
	-     pwbuf[i]     =     chars[random()     %     sizeof(chars)];      +
	pwbuf[i] = chars[rndbuf[i] % sizeof(chars)];
	                pwbuf[i] = '\0';
	                /*