I agree with Peter. If we're concerned about security implications of a particular SW technique then obviously we should ban the C language and all the string libraries first ;-)
John On 10/4/03 1:58, "Peter Gutmann" <[EMAIL PROTECTED]> wrote: > Bill Frantz <[EMAIL PROTECTED]> writes: > >> This is the second significant problem I have seen in applications that use >> ASN.1 data formats. (The first was in a widely deployed implementation of >> SNMP.) Given that good, security conscience programmers have difficultly >> getting ASN.1 parsing right, we should favor protocols that use easier to >> parse data formats. >> >> I think this leaves us with SSH. Are there others? > > I would say the exact opposite: ASN.1 data, because of its TLV encoding, is > self-describing (c.f. RPC with XDR), which means that it can be submitted to a > static checker that will guarantee that the ASN.1 is well-formed. In other > words it's possible to employ a simple firewall for ASN.1 that isn't possible > for many other formats (PGP, SSL, ssh, etc etc). This is exactly what > cryptlib does, I'd be extremely surprised if anything could get past that. > Conversely, of all the PDU-parsing code I've written, the stuff that I worry > about most is that which handles the ad-hoc (a byte here, a unit32 there, a > string there, ...) formats of PGP, SSH, and SSL. We've already seen half the > SSH implementations in existence taken out by the SSH malformed-packet > vulnerabilities, I can trivially crash programs like pgpdump (my standard PGP > analysis tool) with malformed PGP packets (I've also crashed quite a number of > SSH clients with malformed packets while fiddling with my SSH server code), > and I'm just waiting for someone to do the same thing with SSL packets. In > terms of safe PDU formats, ASN.1 is the best one to work with in terms of > spotting problems. > > Peter. > > --------------------------------------------------------------------- > The Cryptography Mailing List > Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED] --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
