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Vulnerability In Firefox Popup Blocker

Posted by kdawson on from the all-your-files dept.

cj writes in with news of a vulnerability in Firefox's stock popup blocker discovered by Michal Zalewski. The vulnerability can allow a malicious user to read files from an affected system. The attacker would "need to plant a predictably named file with exploit code on the target system. This sounds hard, but isn't," according to the article.

13 of 100 comments (clear)

  1. Anyone knows if the 2.x tree is vulnerable too? by A+beautiful+mind · · Score: 5, Informative
    From TFA:

    Vulnerable Systems:
    * Firefox version 1.5.0.9
    Can anyone test?
    --
    It takes a man to suffer ignorance and smile
    Be yourself no matter what they say
    1. Re:Anyone knows if the 2.x tree is vulnerable too? by Tony+Hoyle · · Score: 5, Insightful

      Can anyone test?

      Nope, because no example exploit is given and the means of exploitation looks rather unlikely:

      "To create a popup warning, a script embedded on the page calls: window.open('file:///c:/windows/temp/xxxxxxx.htm', 'new2',''),

      with a name calculated by repeating a procedure implemented in SetUpTempFile() with a seed calculated by the server based on reported system time (p2.html?time)."

      1. It assumes that the temp file is c:/windows/temp. It isn't, unless you're running Windows 95, and only then if you've not changed it from default. That's the *system* default temp file. The *user* temp directory is inside local settings in the user specific area (much harder to find out remotely. Maybe not impossible, but you'd have to get lucky (it's not just the username as the directory name.. it has things like .000 after it).
      2. Calculating the seed to that accuracy is damned hard.

    2. Re:Anyone knows if the 2.x tree is vulnerable too? by rainman_bc · · Score: 3, Informative

      Is anyone still running 1.5.0? I thought the auto upgrade had handled that months ago.

      Fedora has no plans to officially release a 2.0 for FC6:

      http://fedoraproject.org/wiki/Firefox2

      "Fedora users will be to stay with Firefox 1.5 and wait for the Firefox 3.0 update"

      That's left me a bit annoyed personally... I like the changes to FF2...

      --
      09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
    3. Re:Anyone knows if the 2.x tree is vulnerable too? by hal9000(jr) · · Score: 3, Informative

      Yep, on windows. I moved to FF2.0 when it came out, got hosed by java handling and other stuff, and jumped back to 1.5. I will wait a bit longer before I make the leap again.

    4. Re:Anyone knows if the 2.x tree is vulnerable too? by Carnildo · · Score: 3, Interesting

      Thanks for the tip. I just checked my temp directory, and I've got stuff dating back to early 2001 in there.

      --
      "They redundantly repeated themselves over and over again incessantly without end ad infinitum" -- ibid.
    5. Re:Anyone knows if the 2.x tree is vulnerable too? by evilviper · · Score: 3, Insightful

      Also, what's with Windows never deleting anything in the user temp directories? What part of temporary does it not understand?
      As opposed to Linux, which also doesn't clear /tmp?

      Windows is slightly worse, but not by a lot.
      --
      Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
    6. Re:Anyone knows if the 2.x tree is vulnerable too? by Anonymous Coward · · Score: 3, Funny

      Bullshit.

  2. Right... by CasperIV · · Score: 4, Informative

    That was quite possibly the most ignorant statement I have read on slashdot recently. I'm not particularly partial to either Firefox or IE, but exploit for exploit, your statement has no merit. What will be the deciding factor will be how fast it is patched.

    1. Re:Right... by pairo · · Score: 5, Funny

      That was quite possibly the most ignorant statement I have read on slashdot recently.
      You don't really read much of Slashdot, do you?
  3. Windows only? by jimbobborg · · Score: 5, Informative

    From the fine article:

    "When the user chooses to manually allow a blocked popup however, normal URL permission checks are bypassed. "

    So you have to MANUALLY disable the popup blocker on a site you don't know in order to make this work. Also, the article keeps talking about c:\whatever. It does not indicate if this is a vulnerability in a non-Windows system.

    1. Re:Windows only? by Tony+Hoyle · · Score: 5, Informative

      From the text it's hardcoded to a specific installation of Windows (not even the default config). It wouldn't work on most systems.

    2. Re:Windows only? by codepunk · · Score: 4, Funny

      You have to chmod 777 every file in the root and home file systems, log in as root, open a port for ssh, disable ip tables and or ipchains and post the user name (root of course), password and ip to a irc channel, turn off pop up blocking...yep see it effects linux also.

      That is the lamest vulnerability post I have seen in a long time...really stretching here are we not?

      --


      Got Code?
  4. Fixed by Anonymous Coward · · Score: 5, Informative

    Already fixed: https://bugzilla.mozilla.org/show_bug.cgi?id=36942 7