At 8:45 AM -0500 12/30/06, Leichter, Jerry wrote: > [MJoderator: This is likely beyond the point of general interest to sc-l]
Actually, I disagree, in that it seems to expose a set of vulnerabilities not known even to language implementors. > On Fri, 29 Dec 2006, ljknews wrote: > | But these are problems that have been solved by those who provided the > | Ada implementation (ACT and Aonix come to mind for Unix), and thus are > | not an issue for the high level language programmer. > Presumably they do the create-the-file-and-immediately-delete-it trick. > Since the file must, however briefly, have an entry in some directory. > General purpose code can't make assuptions about what directories > are available for writing, so pretty much has to put the entry in > a known, public place - almost always /tmp or /var/tmp. Unless one > does this very carefully, it's open to various attacks. (For one > trivial example, there is no way to tell the open() call to *always* > create a new file - you can only tell it "if the file already exists, > don't open it, return an error instead". The code had better check > for that error and do something appropriate or it can be fooled into > using a file an attacker created and already has access to.) Certainly code that does not check for errors is inadequate. > The techniques for doing this are complex enough - and the attacks > if you don't do it *exactly* right obscure enough - that after all > these years, attacks based on "insecure temporary file creation" > are still reported regularly. (Frankly, even though I know that > these problems exist, if you were to ask me to write a secure > temporary file creator right now, I wouldn't try - I'd look for > some existing code, because I doubt I'd get it right.) Which is what one does when using the existing language implementation (except for the defect reported by Florian Weimer in this thread. -- Larry Kilgallen _______________________________________________ Secure Coding mailing list (SC-L) SC-L@securecoding.org List information, subscriptions, etc - http://krvw.com/mailman/listinfo/sc-l List charter available at - http://www.securecoding.org/list/charter.php SC-L is hosted and moderated by KRvW Associates, LLC (http://www.KRvW.com) as a free, non-commercial service to the software security community. _______________________________________________
