Slashdot Mirror

← Back to Stories (view on slashdot.org)

Red Hat, Google Disclose Severe Glibc DNS Vulnerability; Patched But Widespread

Posted by timothy on from the patched-upstream-that-is dept.

An anonymous reader writes: Today Google's online security team publicly disclosed a severe vulnerability in the Gnu C Library's DNS client. Due to the ubiquity of Glibc, this affects an astounding number of machines and software running on the internet, and raises questions about whether Glibc ought to still be the preferred C library when alternatives like musl are gaining maturity. As one example of the range of software affected, nearly every Bitcoin implementation is affected. Reader msm1267 adds some information about the vulnerability, discovered independently by security researchers at Red Hat as well as at Google, which has since been patched: The flaw, CVE-2015-7547, is a stack-based buffer overflow in the glibc DNS client-side resolver that puts Linux machines at risk for remote code execution. The flaw is triggered when the getaddrinfo() library function is used, Google said today in its advisory. "A back of the envelope analysis shows that it should be possible to write correctly formed DNS responses with attacker controlled payloads that will penetrate a DNS cache hierarchy and therefore allow attackers to exploit machines behind such caches," Red Hat said in an advisory. It's likely that all Linux servers and web frameworks such as Rails, PHP and Python are affected, as well as Android apps running glibc.

4 of 121 comments (clear)

  1. Yet another call for replacement... by dentar · · Score: 5, Insightful

    ... because the proposed replacement will be bug-free, right?

    --
    -- I am. Therefore, I think!
    1. Re: Yet another call for replacement... by Anonymous Coward · · Score: 5, Funny

      He immediately awarded the prize to the second woman.

      Systemd?

  2. Re:Bitcoin? by Anonymous Coward · · Score: 5, Informative

    If you are statically linked AND you do something that results in DNS resolution (like resolving a hostname to IP), then yea, you'd need a recompile. If you are dynamically linked than probably you will pull down a fixed library. Alternatively, they do have a patch. Also they have a workaround you can use if that's impractical, where you limit the DNS size response.

    In the wild this will be nontrivial to exploit because you already choose your DNS servers with some care, and DNS servers are already a target (and therefore reasonably hardened) because of all the phat lewtz you can harvest if you point people to your fake address). So it's a serious vulnerability but not one that could instantly go wormy on us.

  3. Re:Why does a C library need a DNS client? by kthreadd · · Score: 5, Informative

    Doesn't the operating system already have one?

    Yeah it has one, the one in the C library.