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Orcmid's Lair |
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Welcome to Orcmid's Lair, the playground for family connections, pastimes, and scholarly vocation -- the collected professional and recreational work of Dennis E. Hamilton
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2010-05-01Republishing before SilenceThe nfoCentrale blogs, including Orcmid’s Lair, were published through Blogger via FTP transfer to my web sites. That service is ending. Then there will be silence as Blogger is unhooked, although the pages will remain. No new posts or comments will work until I updated the web site to use its own blog engine. Once that migration is completed, posting will resume here, with details about what to know about the transition and any breakage that remains to be repaired. Meanwhile, if you are curious to watch how this works out, check on Spanner Wingnut’s Muddleware Lab. It may be in various stages of disrepair, but that blog will come under new custodianship first. Labels: web site construction ¶ posted by orcmid at 5/01/2010 01:26:00 AM from: 2010-04-17… And It Came to PassProphets in Their Own LandsBack in February, I posted “Document Security Theater: When the Key is More Valuable than the Lock.” I was objecting to a technique, now being immortalized in open-document formats such as ODF and OOXML, whereby a hashed copy of a password is stored in the document such that it can easily be retrieved and used to attack the password itself. As explained there, the value of the password is not in being used to overcome the protection of the document against alteration – that is easy to do without ever bothering to know the password. The value of the password is that it is a memorable secret of the password holder and it needs to be protected (i.e., disguised) because it is also used for a variety of valuable purposes. The failure to achieve a separation of concerns is probably a tip-off here. Either way, the exposure of hashed copies of passwords is not a new issue. There are available expert reports that identify the flaw. Attacks on passwords whose hashed copies are known have been popular since the first widespread Internet worm was released against unprotected systems. For example, the Unix /etc/passwords file with its hashed copies of passwords was commonly readable by all users and certainly anywhere once a root password was compromised. That users had the same passwords on different systems made leap-frog attacks from system-to-system particularly promising. It is like watching an elaborate arrangement of dominoes fall. Encouraging Gullible ConductMy argument then was that it is folly to increase the complexity of hash coding and believe that the password is thereby protected against discovery by a determined attacker. The defect in reasoning is in the assumption that the remedy to attackable hashed password copies is to use a “stronger” hashing technique. It does not make a memorable password stronger, and there is effectively a (disguised) copy of the password in plain sight. Having the copy and knowing the hashing technique allows that still-weak password to be attacked about as easily as it ever could be. Systems which use password hashing as a way of not keeping passwords around in plaintext also arrange to secure the hashed copies against discovery. Once the hashed copies are known, discovery of the password is becoming child’s play, especially for memorable passwords that are reused by the password holder as a matter of convenience. We’ve all learned by now that convenience trumps security, right? My objection is against willfully pandering to that conduct. You can imagine my dismay when my efforts to end that perpetration in the ODF specification were rebuffed by this argument: “The justification for stronger algorithms than SHA1 is that many users use the same passwords for multiple tasks. So, it is worth to protect the key. Since we explicitly added the [SHA256 and stronger hashing methods] attributes to ODF 1.2 on request, we should not revert this.” That is precisely the reason we should “revert” that so far draft-only provision of ODF 1.2. Reality Will Not Be FooledLast week, there was announcement that some servers at Apache.org had been attacked and compromised. I saw notices such as ZDNet’s “Apache.or hit by targeted XSS attack, passwords compromised” and PCWorld’s (via Yahoo) “Apache Project Server Hacked, Passwords Compromised.” I didn’t read the articles, since it was about an all-too-common sort of break-in. What I didn’t appreciate was that the attackers stole lists of user names and their hash coded passwords. What finally caught my undivided attention was the 2 | ||