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Corrupted Attachments

Printed From: LogSat Software
Category: Spam Filter ISP
Forum Name: Spam Filter ISP Support
Forum Description: General support for Spam Filter ISP
URL: https://www.logsat.com/spamfilter/forums/forum_posts.asp?TID=1011
Printed Date: 18 October 2024 at 7:26am


Topic: Corrupted Attachments
Posted By: Guests
Subject: Corrupted Attachments
Date Posted: 19 June 2003 at 3:06pm

We have been experiencing intermittent corruption of PDF files sent as attachments, and blaming Outlook 2000. However, we now find that it's Spamfilter ISP doing it. We've tried version 1.1.2.124 as well as the new beta, with the same result.

We've tracked it down to certain PDFs, not all, but the result is consistent no matter how many times we try, with or without other PDF attachments that get through fine. It looks like every occurrence of the hex sequence "0A 2E" is being truncated to "0A" throughout the file. The real mystery is that other PDFs get through all right with that sequence unscathed.

Anybody else have similar problems?

Thanks.

 


Replies:
Posted By: LogSat
Date Posted: 19 June 2003 at 3:29pm

Tony, if you email us at mailto:support@logsat.com" CLASS="ASPForums" TITLE="WARNING: URL created by poster. - support@logsat.com one such PDF that get corrupted we'll try to replicate the problem. Please place it in a zip file otherwise it will arrive to us corrupted since we are using SpamFilter as well...

Roberto Franceschetti
LogSat Software

Posted By: LogSat
Date Posted: 21 June 2003 at 12:33am
Tony,
 
Thanks for identifying and reporting the bug. We've indeed verified it earlier today and have a patch ready. In our internal tests it seems to have fixed the problem. We'll release it to the public most likely this weekend after more testing is done.
 
Roberto Franceschetti
LogSat Software

Posted By: Desperado
Date Posted: 21 June 2003 at 7:51pm

Personal question.  How in the world did you find that exact sequence of corruption?  I had just started to look at this issue when your post came through.

Dan S.

Posted By: Guests
Date Posted: 23 June 2003 at 2:43pm

Not too difficult, really. I did a plain old file compare between an original and the munged copy, noted a pattern in the discrepancies, then used a hex editor and searched for the unique strings immediately preceding the differences. After checking a few like this, the pattern leapt out. Confirmed no other munging by counting the string instances in the original and getting the exact byte difference between the two. It didn't happen to every file with that string, though, so I'm presuming there was something in the PDF header that triggered it.

The fine LogSat techs nailed it, though, and deserve kudos for blazing fast resolution. You certainly wouldn't find such technical support responsiveness from the likes of McAfee et al.

Great product, folks.

Cheers.

 

 


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