ASIDONHO@JHUIGF.BITNET.UUCP (08/28/87)
Replying to a couple of messages recently appearing:
One was about how careful one has to be with privileged
images. I have noticed an additional precaution that must be made with
images written in FORTRAN, and I have the feeling this problem may
exist at many sites.
Fortran unit numbers are pointed to by logical names "FORNNN".
If these names are not defined, the RTL will use files "FORNNN.DAT",
but in the case of for005 and for006, it will use sys$input and
sys$output. Suppose there is a program installed with sysprv, that
uses fortran units 5 and 6 for terminal output without expicitly
opening them. Any user can redirect these units at DCL level to create
or read files with sysprv by assigning for005 and for006. It may be
true that the program's operations are determined by the programmer,
but just the capability of creating a new sys$share:dcltables.exe
simply containing the output of some program is pretty harsh.
I have found the problem can be avoided if units 5 and 6 are
explicitly opened as sys$input and sys$output. Since these are open
at the dcl level, the file open is done immediately with the assign
command, not after the privileged program starts up.
In another totally unrelated message, someone said they were
having problems with vmsshar checksums. I also have these problems.
I have noticed that any mail I receive from bitnet/jnet has blank
lines converted to four spaces! Possibly lines shorter than 4 char.
are also padded, but I didn't check. Perhaps vmsshar could be modified
to take this into account.
-Tom O'Toole
Interactive Graphics Facility
J.H.U Med. School
Balto. Md. 21205