[comp.sys.att] UNIX-PC Phone-Setup Security Bug

eed_wwhh@jhunix.UUCP (William H. Huggins) (12/14/87)

After one has set the protection mode on  L.sys  to the proper

-rw-r-----  1 uucp    mail       1960 Dec 12 12:10 /usr/lib/uucp/L.sys

if the Install Phone-Setup menu is used to change from two
phone lines to just one, the protection mode on L.sys will be
altered to

-rw-r--r--  1 root    users      1959 Dec 12 12:52 /usr/lib/uucp/L.sys

Apparently, the Phone-Setup script reads  L.sys and also  L-devices 
to change  "ph1"  to  "ph0"  and in the process writes NEW VERSIONS of  
L.sys and L-devices  WITHOUT RESTORING their protection modes to their
prior settings.  (Hence, owner  becomes  root  and  group  becomes users, 
with protection mode set to  644  instead of 640 as previously defined.)

Thereafter, the secret passwords in  L.sys  are generally accessible
to any user after the Phone-Setup menu has been activated.

-- 
W.H. Huggins (EED)


-- 
W.H. Huggins (EED)