Run the following Python script, on Unix/Linux:

==========
import zipfile

z = zipfile.ZipFile('zipbad.zip', 'w')
z.writestr('filebad.txt', 'Some content')
z.close()

z = zipfile.ZipFile('zipgood.zip', 'w')
zi = zipfile.ZipInfo('filegood.txt')
zi.external_attr = 0660 << 16L
z.writestr(zi, 'Some content')
z.close()
==========

Like this:

python testzip.py  && unzip zipbad.zip && unzip zipgood.zip && ls -l
file*.txt

You'll see:

----------  1 swarren swarren   12 2008-07-17 12:54 filebad.txt
-rw-rw----  1 swarren swarren   12 1980-01-01 00:00 filegood.txt

Note that filebad.txt is extracted with mode 000.

The WAR (used for filegood.txt) is to pass writestr a ZipInfo class with
external_attr pre-initialized. However, writestr should perform this
assignment itself, to be consistent with write. I haven't checked, but
there's probably a bunch of other stuff in write that writestr should do
too.