Description:
------------
I was reading some of the zip files here:
and stumbled across this line: https://github.com/php/php-src/blob/master/ext/zip/php_zip.c

[snippet]
ret = php_stream_mkdir(pathto, 0777,  PHP_STREAM_MKDIR_RECURSIVE, NULL);
[/snippet]

which creates the directory (provided in the extractTo parameter) with 777 permissions.

Moreover, during zip extraction(in php_zip_extract_file()): all of the directories are extracted with 777 permissions:
[snippet]
ret = php_stream_mkdir(file_dirname_fullpath, 0777,  PHP_STREAM_MKDIR_RECURSIVE|REPORT_ERRORS, NULL);
[/snippet]

Anything that is not a directory is extracted with 664 permission (which allows everyone to read, i.e: rw-rw-r-- )

The combination of all of these things allows a malicious user on the same linux server to read the extracted files (because of the 664 permissions) and list the directories' info because of the 777 permissions, which allows easy navigation and make the attack surface even bigger. 

Recommendation: I would suggest one of the following:
1. Remove public access by default. Change the permissions to 660 and let the programmer use chmod() by himself if he really want to share those extracted files with everyone. 
2. Alternatively, Set the default file permission to be a configureable thing (instead of hard-coded)






Test script:
---------------
<?php
$zip = new ZipArchive;
if ($zip->open('test.zip') === TRUE) {
    $zip->extractTo('/tmp/phpfuzz/outdir/');
    $zip->close();
    echo 'ok';
} else {
    echo 'failed';
}
?>

Expected result:
----------------
(notice the permissions)

drwxrwxr-x 3 ryanc ryanc 4096 Mar 14 11:26 outdir
  |
  |  drwxrwxr-x 3 ryanc ryanc 4096 Mar 14 11:26 directory1
          | -rw-rw---- 1 ryanc ryanc    4 Mar 14 11:26 secret1.txt
          |
          | drwxrwx--- 2 ryanc ryanc 4096 Mar 14 11:26 directory2
             | -rw-rw---- 1 ryanc ryanc    4 Mar 14 11:26 secret2_recursive.txt

Actual result:
--------------
(notice the permissions)

drwxrwxr-x 3 ryanc ryanc 4096 Mar 14 11:26 outdir
  |
  |  drwxrwxr-x 3 ryanc ryanc 4096 Mar 14 11:26 directory1
          | -rw-rw-r-- 1 ryanc ryanc    4 Mar 14 11:26 secret1.txt
          |
          | drwxrwxr-x 2 ryanc ryanc 4096 Mar 14 11:26 directory2
             | -rw-rw-r-- 1 ryanc ryanc    4 Mar 14 11:26 secret2_recursive.txt