Various FA Vulnerabilities that need to be addressed

@itronics: Thanks for the quick commits in FA 2.3 and FA 2.4. There seem to be some files left out.

The file includes/main.inc is expected to be included in every instance where it is used as the new function random_id() is defined there and it refers to a variable $cstrong which is not assigned yet. This is mostly okay as it is a return diagnostics value only. If there are any errors then just assign it a blank string before invocation as it is passed by reference.

The following files too use uniqid still and no changes in them yet in the commit done now:
1. includes/ui/ui_view.inc - $name = uniqid('_el',true);
2. reporting/includes/class.mail.inc - $this->boundary = md5(uniqid(time()));
3. reporting/includes/tcpdf.inc - $owner_pass = uniqid(rand());

4. sales/includes/cart_class.inc - $this->cart_id = uniqid(''); - This is just temporary cart id used to avoid erroneous concurrent edition inside single user session. This is not used in urls, so the security problem does not apply here.

In FA 2.4 additionally:
1. includes/dashboard.inc - $filename = company_path(). "/pdf_files/". uniqid("").".png"; - Fixed in this commit.

When changes are made to the files above, we need to make sure that the said new function random_id() is available therein. Those using it in extensions and using SOAP / RESTful APIs too need to take care by defining the function if it dows not exists at the point of invocation.

@itronics: please replace line 372 in FA 2.3's includes/main.inc:

    $id = strtr(base64_encode($bin), '+/', '-_');    // see RFC 4648 Section 5

with

    $id = strtr(base64_encode($bin), '+/=', '-_x');    // see RFC 4648 Section 5

and likewise in FA 2.4. The pad character "=" can be got rid off this way.
Before your commit, it was a 13 character file base name and it is now 24 (multiples of 8).
The original filename was like:
    dLPhO1A-K5vj5Dq4NxBA7w==.pdf
and the new file name will be like:
    4vuNUMXvAVsQVuHEVzlrdwxx.pdf

** Fixed in FA 2.3 and FA 2.4 commits.

Consistent Excel Report download SOLVED!

First we need to include the fix in post 4 of this thread.
The issue of filenames starting with a hyphen or underscore may need to be addressed.
The function clean_file_name() in includes/main.inc can also do the job.

Since we are now allowing underscores(_) and hyphens (-) in the random_id()'s filenames, we need to allow it for excel filenames for download too.

Lines 30 to 55 in FA 2.3's reporting/prn_redirect.php:

if (isset($_GET['xls']))
{
    $filename = $_GET['filename'];
    $unique_name = preg_replace('/[^0-9a-z.]/i', '', $_GET['unique']);
    $path =  company_path(). '/pdf_files/';
    header("Content-type: application/vnd.ms-excel");
    header("Content-Disposition: attachment; filename=$filename" );
    header("Expires: 0");
    header("Cache-Control: must-revalidate, post-check=0,pre-check=0");
    header("Pragma: public");
    echo file_get_contents($path.$unique_name);
    exit();
}
elseif (isset($_GET['xml']))
{
    $filename = $_GET['filename'];
    $unique_name = preg_replace('/[^0-9a-z.]/i', '', $_GET['unique']);
    $path =  company_path(). '/pdf_files/';
    header("content-type: text/xml");
    header("Content-Disposition: attachment; filename=$filename");
    header("Expires: 0");
    header("Cache-Control: must-revalidate, post-check=0,pre-check=0");
    header("Pragma: public");
    echo file_get_contents($path.$unique_name);
    exit();
}

can be replaced with:

if (isset($_GET['xls']) || isset($_GET['xml']))
{
    $filename = $_GET['filename'];
    $unique_name = preg_replace("/[^0-9_a-z.\-]/i", '', $_GET['unique']);
    $path =  company_path(). '/pdf_files/';
    if (isset($_GET['xls'])) header("Content-type: application/vnd.ms-excel");
    else header("content-type: text/xml");
    header("Content-Disposition: attachment; filename=$filename" );
    header("Expires: 0");
    header("Cache-Control: must-revalidate, post-check=0,pre-check=0");
    header("Pragma: public");
    echo file_get_contents($path.$unique_name);
    exit();
}

@joe: please update both repos.

PHP PCRE (Regular Expressions) - CheatSheet | Tutorial.