New issue
Advanced search Search tips
Note: Color blocks (like or ) mean that a user may not be available. Tooltip shows the reason.
Starred by 3 users

Issue metadata

Status: Fixed
Last visit 20 days ago
Closed: Sep 2016

Sign in to add a comment

Symantec: Heap overflow modifying MIME messages CVE-2016-3644

Project Member Reported by, May 4 2016

Issue description

Symantec attempts to clean or remove components from archives or other multipart containers that they detect as malicious. The code that they use to remove components from MIME encoded messages in CMIMEParser::UpdateHeader() assumes that filenames cannot be longer than 77 characters.

This assumption is obviously incorrect, names can be any length, resulting in a very clean heap overflow.

The heap overflow occurs because Symantec does the cleaning in multiple stages, first changing the Content-Type to "text/plain", then changing the filename to "DELETED.TXT". The problem is that during the first stage of this process, they maintain the existing name but use a buffer prepared for the final name.

Something like:

char *buf = malloc(strlen(NewContentType) + strlen(LengthOfNewEncodedFilename) + 100)

// First change the content-type
strcpy(buf, "Content-Type: ");
strcpy(buf, NewContentType;
strcpy(buf, "; name=\"");
strcpy(buf, OldFileName);

UpdateName(buf, NewFileName);

This obviously won't work, because it doesn't verify that the old name will fit. I've attached an example MIME message that triggers this code in Symantec Scan Engine.

This bug is subject to a 90 day disclosure deadline. If 90 days elapse
without a broadly available patch, then the bug report will automatically
become visible to the public.
483 bytes Download
Project Member

Comment 1 by, Jun 28 2016

Labels: -Restrict-View-Commit
Disclosure date reached, unrestricting bug.
Project Member

Comment 2 by, Jun 28 2016

Summary: Symantec: Heap overflow modifying MIME messages CVE-2016-3644 (was: Symantec: Heap overflow modifying MIME messages)
Project Member

Comment 3 by, Sep 20 2016

Status: Fixed (was: New)

Comment 4 Deleted

Sign in to add a comment