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Microsoft Bypasses HOSTS File

whitehatlurker writes "Dave Korn announced on the Full Disclosure and Bugtraq security lists that Microsoft is bypassing local lookups for some hosts, meaning that you can't locally block some sites through your HOSTS file. All of these sites are MicroSoft controlled sites. The general feeling in the rest of the thread is that this was to obfuscate these hosts and prevent them from being blocked by malware. However, there are no non-MicroSoft hosts listed, giving a competitive advantage for MicroSoft's anti-malware tools over other brands."

35 of 459 comments (clear)

  1. Not a useful thing for MS to do by mgv · · Score: 5, Interesting

    I would have thought that if you cant subvert the HOSTS file then all you have to do is to intercept any DNS lookup of these MS addresses and you would have the same effect.

    If you are trying to stop MS software from talking to home, then just use an external firewall.

    Michael

    --
    There is no cryptographic solution to the problem where the intended receiver and the attacker are the same entity.
    1. Re:Not a useful thing for MS to do by whoever57 · · Score: 3, Interesting

      What is there to stop a virus making edits to the dll binary? Changing the strings that presently correspond to the IP addresses of MS domains to some random, invalid address?

      --
      The real "Libtards" are the Libertarians!
    2. Re:Not a useful thing for MS to do by x0n · · Score: 4, Informative

      >What is there to stop a virus making edits to the dll binary? Changing the strings that presently
      >correspond to the IP addresses of MS domains to some random, invalid address?

      Yes, there is a mechanism built into Windows which uses digital signatures and a watchdog to prevent accidental (or deliberate) changes to sensitive DLLs. Any binary changes to any file will invalidate the signature on the DLL. This is more effective than tripwire or other such things whereby a checksum is held in another location since the DLL itself is signed using a PK and cannot be re-signed to hide the changes.

      Windows File Protection: http://support.microsoft.com/?kbid=222193

      - Oisin

      --

      PGP KeyId: 0x08D63965
  2. Is this necessarily a bad thing? by BluhDeBluh · · Score: 5, Interesting

    It helps prevent Malware. Sure, MS might have a slim advantage, but it also prevents otherwise botted PCs from accessing MS Updates against things like Blaster. I don't see this as being such a big deal.

    1. Re:Is this necessarily a bad thing? by Morvandium · · Score: 5, Informative

      I agree. In addition, as much as I may think they should include other sites on that list, those other sites do not play into what MicroSoft sees as the "integrity" of their product. They're not out to make sure that you can get the latest update of Apache or OpenOffice or whatever; they want to make sure that you can update Windows to the latest version (one that might actually stop the malware they're trying to protect from) or get to a place where you can ask MicroSoft a question (which they may or may not answer, and if they do, the answer to which may or may not be helpful), or, heaven forbid, get to a place where you can order a new MicroSoft product (probably because you haven't realized it will have similar flaws to your current and older MS products).

      --
      "If God's on our side, he'll stop the next war." -- Bob Dylan
    2. Re:Is this necessarily a bad thing? by quarkscat · · Score: 5, Insightful

      Absolutely, yes, it is a bad thing.

      Microsoft has:
              instituted not only License 6, but also "phone home" validation. At any time, MS may
              decide to shut down any business worldwide that uses their products, at their (or a
              malviolent government's) discretion;

              embraced and extended(tm) LDAP with kerberos authentication that is not industry-
              standard or cross-platform compatible;

              embraced and extended(tm) web browser standards that have made Internet and
              platform security a nightmare;

              implimented a software firewall (XP SP2) that doesn't actually control/restrict all
              incoming and outgoing packets, making the use of a third party (H/W?) firewall
              less redundant and more actually necessary;

              stripped nearly all OS improvements out of their upcoming flagship OS, excepting
              Digital Rights Restrictions -- which may also remotely disable or remove products
              and/or services which they choose to disallow for any reason.

      Bypassing DNS and the hosts file on the OS platform is their "camel's nose under the
      tent flap" for future modifications to the network stack, all in the name of their brand
      of "security", which is (frankly) appalling. Given Microsoft's current product direction,
      it is not outside the realm of possibility that the future average computer user's
      experience will be some cross between a WebTV and an XBox.

    3. Re:Is this necessarily a bad thing? by DrSkwid · · Score: 5, Funny

      > I didn't even know about the hosts file until 5 minutes ago

      and already you feel qualified to comment

      --
      There are places where the networks are not touching,and there are places where they are-Boeing's Lori Gunter
  3. So what? by nametaken · · Score: 4, Insightful

    People should know by now, when you go MS, you don't buy the horse, you buy the farm. You wanna segment and pick and choose on the MS platform? Good luck.

    1. Re:So what? by Aaden42 · · Score: 5, Funny

      No, no... You just *license* the farm. MS still owns it. For a nominal fee, they'll let you step in the cow pies every second Tuesday.

  4. Ad blocking by aembleton · · Score: 5, Interesting

    Microsoft could also be using this to prevent users from blocking MSN messenger ad servers.

  5. Permissions? by tomstdenis · · Score: 4, Insightful

    tom@localhost ~ $ ls -l /etc/hosts
    -rw-r--r-- 1 root root 519 Oct 19 12:13 /etc/hosts

    ....

    Why can't windows just make the host files read only.

    --
    Someday, I'll have a real sig.
    1. Re:Permissions? by tomstdenis · · Score: 4, Insightful

      Yes, but the motivation to ignore the hosts file is because of viruses that could overwrite it.

      So ... if a user level virus couldn't write to the host file ...

      Think about it.

      Tom

      --
      Someday, I'll have a real sig.
    2. Re:Permissions? by v1 · · Score: 4, Insightful

      Windows security is as effective as a screen door on a submarine.

      It'd take the malware makers about an hour to find any of the what, probably 80 holes that would let them go around such windows security. A back-and-forth battle like that could easily go on for months if not years. In unix, security and permissions are the foundation, on top of which everything is built. In windows, security is a hack that was added on later with no due consideration during the initial design phase of windows. It's no wonder it's next to impossible to get it to work the way you want it to.

      When you are designing security, the sad truth of it is, the user is the enemy. There's no nicer way to look at it. So it takes a great deal of care to design a security system that can withstand the assult of a user while at the same time being functional and serving the user. It's too late for windows to make those design considerations. They have errored on the side of functionality and sacrificed the security of the system. There is no fixing that.

      --
      I work for the Department of Redundancy Department.
    3. Re:Permissions? by secolactico · · Score: 4, Insightful

      So ... if a user level virus couldn't write to the host file ...

      Which leads us back to the primordial Windows security problem: users running with admin priviledges.

      In the example you provided in the previous post, /etc/hosts is writable only by root. If user runs as root all the time, then it's back to square one.

      As far as I know Windows host file is only writable by Administrator level (dunno, I don't have a Windows machine with me right now). Is it otherwise?

      --
      No sig
    4. Re:Permissions? by saleenS281 · · Score: 5, Insightful

      funny, I see write access by root there. And last I checked, when malware *owns* windows, it's local root, which means the permissions you speak of would amount to absolutely nothing... And btw, you can make it read only to normal users, but again, this would accomplish nothing.

    5. Re:Permissions? by Homology · · Score: 5, Funny
      So ... if a user level virus couldn't write to the host file ...

      Think about it.

      Dear Tom,
      this is Slashdot and the term "think" does not apply.

    6. Re:Permissions? by Foolhardy · · Score: 3, Informative
      On Windows Server 2003 SP1:
      C:\WINNT\system32\drivers\etc\hosts
      BUILTIN\Users :R
      BUILTIN\Power Users:R
      BUILTIN\Administrators:F
      NT AUTHORITY\SYSTEM:F
      Normal and power users get read, Administrators and SYSTEM get full control, all inherited from the drivers directory.

      You're absolutely right about the root problem as running everything as admin. Almost all the malware that I've seen fails miserably unless run as admin, and that which does run can't infect the entire system. I guess the users that know enough to run as a normal user are the same ones that avoid that crap in the first place.
  6. It's a Big Deal because... by TubeSteak · · Score: 5, Insightful
    As mentioned in TFA's thread:
    2) As far as I know, their malicious software removal tool didn't exist back when this behavior was created, so what good was keeping access to Microsoft open going to do an infected system? What good does it do to install a patch for a vulnerability that's already been exploited onto the computer of the archetypal "home user"?
    MS hardcoded this in with WinXP SP2 & Win2k3 SP1.

    Why? Maybe someone will get a comment from MS.

    The point is that mucking around with the inner workings of the OS is BAD, unless it is documented appropriately. Now, documentation doesn't make it good, but if they're departing from the expected behavior, they should let people know.
    --
    [Fuck Beta]
    o0t!
  7. Potentially unfair... by Maul · · Score: 5, Insightful

    The main problem is not that you can't block MS addresses, it is that MS is only preventing their addresses from being blocked. Since they are now getting into the security business, this gives them what could be seen as an unfair advantage.

    Let us say that Joe User gets a piece of Malware, so he decides to visit a security company to find a solution to his problem. However, the malware has modified his hosts file to block security company web pages from being accessed, which is extremely typical. Joe User is not experienced enough to even know there is a hosts file that he could change back.

    Joe User's first attempt would likely be to norton.com, symantec.com (both go to Symantec's main page), or mcafee.com, since these names are pretty much synonymous with antivirus software. However, all of those are blocked and he can't access them.

    However, if he goes to microsoft.com, he can go there since the hosts file is subverted in the OS. Since he can't spend the time to figure out why he can't access the others, he purchases Microsoft's AV solution.

    --

    "You spoony bard!" -Tellah

  8. Yet Another Band-Aid? by displaced80 · · Score: 4, Insightful

    Hmm. This seems a bit ass-backwards to me.

    Rather than having to ignore the HOSTS file because it may be malicious, shouldn't the solution be to prevent HOSTS from getting mangled in the first place?

    (oh, and on an unrelated note: why on earth is the Win32 HOSTS file buried away under C:\Windows\System32\Drivers\etc\? I mean.... 'drivers'?!!? Bizarre.

    --
    What's the frequency, Kenneth?
    1. Re:Yet Another Band-Aid? by idesofmarch · · Score: 5, Informative

      The solution exists. Running as standard user in Windows XP will prevent changes to the hosts file.

    2. Re:Yet Another Band-Aid? by moosesocks · · Score: 4, Interesting

      I've always found the /etc/ to be the funniest part of that path.

      This is one of the telltale remaints of the BSD-derived TCP/IP stack that NT/XP uses.

      Although the stack itself has been heavily modified, using /etc/ as the location for the hosts file still remains, along with other little hints -- ftp.exe is almost identical to the BSD FTP utility. BSD also gets properly credited in the XP copyright notice

      --
      -- If you try to fail and succeed, which have you done? - Uli's moose
  9. Smart move from M$ by Fantasio · · Score: 3, Insightful
    How long before somebody poisons these adresses in the DNS servers ?

    An automatic update of WMP and your PC gets owned, and nothing can be done to prevent it!

  10. Would be ok... by thefogger · · Score: 3, Insightful

    ...if Microsoft had documented this behavior. Yet still, I fail to see what the big deal is. So you can't force an IP address to a domain with hosts.txt for some sites that microsoft controls. If you need to do that, for example for some corporate filter or updating solution, you could just modify your own dns server. Home users on the other hand get more reliable access to windows update, which is very important. Otherwise it would be trivial for malware to block the computer from recieving updates, and the automatic updates would silently fail.

    Cheers, Fogger

    --


    Um... I didn't do it!
  11. Route to null by PlusFiveTroll · · Score: 5, Informative

    If the adware can change your hosts file then this is pretty useless anyway. Now all the software has to do is run a script that does the following

    nslookup whatever.microsofts.domains
    takes the list of return addresses and
    route ADD destination MASK mask INVALID INVALID INVALID foreach

    and your traffic to MS wont even leave the network card.

  12. Interference with my sig! by Teun · · Score: 3, Funny
    How nasty of MS to interfere with my sig!
    Now I'll have to include a disclaimer...

    Just another reason to continue using a more robust system :)

    --
    "The likes of Facebook and WhatsApp are free to those whose privacy is of zero value."
  13. Sensationalism by Anonymous Coward · · Score: 3, Insightful

    Who cares?

    Nothing prevents you from not using the operating system's resolver. Its trivial to implement your OWN DNS client in your programs, bypassing any HOSTS settings and other DNS resolver issues.

    I've never seen so many people who were so clueless and misinformed about the technical issues involved here.

  14. I couldn't reproduce this on Win2K. by khasim · · Score: 3, Interesting

    I'm wondering if the behaviour will change if you just go into "services" and disable the DNS client.

    I recommend this anyway. In theory it will increase the number of requests your machine does. But in practice it has saved me a lot of "try rebooting" calls.

    Anyone out there with XP who can reproduce this?

    1. Re:I couldn't reproduce this on Win2K. by pla · · Score: 4, Interesting

      Anyone out there with XP who can reproduce this?

      Good idea, but no luck. Same result, though with one slight difference which might prove useful as a workaround - The first attempt timed out, meaning it really performs the query rather than having a hardcoded list of IP mappings. So if you ran a cacheing DNS proxy on your machine (ie, exactly what the built-in DNS service does, but one not containing a built-in Microsoft hack), pointed your machine's DNS to itself, and tell the proxy to use a bogus address for the sites in question, that should successfully block them.

      Better to do this at the firewall, though (a real external hardware firewall, not Microsoft's "trust us, this works" crap).

  15. Monopolies by Tony · · Score: 5, Insightful

    A court of law has determined that Microsoft is a monopoly. One of the anti-trust regulations specifies that you cannot use your monopoly power to force your way into another market; that was the heart of the conviction against Microsoft in the Netscape case. Microsoft used their monopoly to oust Netscape as the dominant browser by bundling, which is illegal.

    Now they are using that same monopoly power to take over the anti-malware market.

    I'm rather ambivilent about this. On one hand, it is just one more case of Microsoft waiting for a market to mature, then forcing their way into it. On the other hand, this market wouldn't exist if it wasn't for their own shoddy products, so it's really Microsoft's reponsibility to fix it. However, malware protection software isn't the correct answer, it's just the most expedient, with a potential for additional profit.

    All-in-all, it's just Microsoft's usual game: own the system, rig the system, use that to take over another system. Keep secrets, and act all coy when your secrets are discovered.

    --
    Microsoft is to software what Budweiser is to beer.
    1. Re:Monopolies by toddestan · · Score: 3, Insightful

      How did Microsoft financially benefit from Internet Explorer's dominance? IE is and always has been a free product. More relevant to this topic

      Back in the day, Netscape was developing web applications. This was kind of scary for Microsoft, as this shifted the focus away from the operating system and to the browser. Back then, Netscape ran on almost everything (Windows, Mac, Linux, BSD, OS/2, etc), and if in the future the user did all their work under web applicatons, then suddenly the underlying OS would become less important. Why spring for a Windows license to run Netscape when you could download Linux for free?

      So Microsoft's response was Internet Explorer. At first it seemed that Microsoft was going with the Netscape route of supporting multiple platforms, but they quickly killed off everything but IE for Windows (Except for the Mac version, which lingered on quite a bit longer before finally getting axed). From there they made their browser not quite standards compliant (but close enough to get people to switch to it), and created ActiveX. They then integrated all of this into Windows and their respective server software. This made it easy for people to create Web applications and content that only worked properly under Internet Explorer for Windows, and many of these ended up being made - particularly for company intranets. At first, this seemed great for companies that basically ran Windows everywhere, but it also locked them into Microsoft's software. This is likely one of the reasons why Windows is still so dominant on the desktop, and is also one of the main reasons why in the bizarro-land of slashdot circa April, 2006, Mac users are so excited about running Windows on their Apple machines.

      Of course, the threat of Web applications is coming around again, with open standards like XML threating to make your choice of OS less revelevent, and even your choice of browser unimportant (so long as it supports the open standards). I'm not sure what Microsoft has in store for this round (if anything), as IE7 seems to be too little, too late - and the popularity of Linux and OSX growing.

      So in conclusion, Internet Explorer wasn't so much about crushing Netscape Navigator, as it was about crushing Web applications that could run everywhere.

  16. Re:MSN by mrraven · · Score: 3, Informative

    20 dollars, try free, like AVG. AVG is pretty nice it operates in stealth mode so your computers ports are invisible to probes and alerts you when any new program tries tries to phone home. And no I'm not affiliated or invested in AVG in any way I just think it's cool they make a good firewall available for free.
    Yes it's propitiatory and closed source but at least free as in beer, shrug.
    Anyway I only run Windows in a virtual pc. sandbox so it won't infect my real O.S.

    --
    Tired of all the isms, don't exploit people as an employer, or a government, mmmmK?
  17. Re:They control the haiku by Psykechan · · Score: 3, Interesting

    (And my troll is in Haiku)

    Windows xp still better
    need to run useful software
    Mac and Linux are toys


    that is not quite right
    both the troll and the haiku
    are somewhat lacking

    but please understand
    Mac and Linux are not toys
    just other systems

    Windows has problems
    while it does have more software
    it is insecure

    please try something else
    you might find that you like it
    don't stagnate yourself

    if end users switch
    developers will follow
    more software for all

    so please help yourself
    and help the rest of the world
    try something else

    if you don't like them
    that is your prerogative
    simply don't use them

    but I'm warning you
    going back is much harder
    but it is your choice

    other OSes
    few viruses and malware
    true computing bliss

    as for poetry
    haiku sylable count is
    5-7-5

  18. Re:WHY? by Mister+Transistor · · Score: 4, Funny

    IIRC, it's a hangover from Windows 3.1 or maybe Win95.

    --
    -- You are in a maze of little, twisty passages, all different... --
  19. ANYONE can Do this! The Functions are Documented by ZOverLord · · Score: 3, Informative

    Just look Here for more info:

    http://msdn.microsoft.com/library/default.asp?url= /library/en-us/dns/dns/dnsquery.asp

    Also you can defeat a Host file by simply changing the priority of lookups using the registry, more here:

    http://www.dslreports.com/forum/remark,15900699~da ys=9999~start=20#15902844

    --
    Black Gray White Hats Unite to protect http://testing.OnlyTheRightAnswers.com