metadata/glsa/glsa-201612-02.xml


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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE glsa SYSTEM "http://www.gentoo.org/dtd/glsa.dtd">
<glsa id="201612-02">
  <title>DavFS2: Local privilege escalation</title>
  <synopsis>A vulnerability in DavFS2 allows local users to gain root
    privileges.
  </synopsis>
  <product type="ebuild">davfs2</product>
  <announced>2016-12-02</announced>
  <revised count="1">2016-12-02</revised>
  <bug>485232</bug>
  <access>local</access>
  <affected>
    <package name="net-fs/davfs2" auto="yes" arch="*">
      <unaffected range="ge">1.5.2</unaffected>
      <vulnerable range="lt">1.5.2</vulnerable>
    </package>
  </affected>
  <background>
    <p>DavFS2 is a file system driver that allows you to mount a WebDAV server
      as a local disk drive.
    </p>
  </background>
  <description>
    <p>DavFS2 installs “/usr/sbin/mount.davfs” as setuid root. This utility
      uses “system()” to call “/sbin/modprobe”.
    </p>
    
    <p>While the call to “modprobe” itself cannot be manipulated, a local
      authenticated user can set the “MODPROBE_OPTIONS” environment
      variable to pass a user controlled path, allowing the loading of an
      arbitrary kernel module.
    </p>
  </description>
  <impact type="normal">
    <p>A local user could gain root privileges.</p>
  </impact>
  <workaround>
    <p>The system administrator should ensure that all modules the
      “mount.davfs” utility tries to load are loaded upon system boot
      before any local user can call the utility.
    </p>
    
    <p>An additional defense measure can be implemented by enabling the Linux
      kernel module signing feature. This assists in the prevention of
      arbitrary modules being loaded.
    </p>
  </workaround>
  <resolution>
    <p>All DavFS2 users should upgrade to the latest version:</p>
    
    <code>
      # emerge --sync
      # emerge --ask --oneshot --verbose "&gt;=net-fs/davfs2-1.5.2"
    </code>
  </resolution>
  <references>
    <uri link="https://nvd.nist.gov/nvd.cfm?cvename=CVE-2013-4362">CVE-2013-4362</uri>
  </references>
  <metadata tag="requester" timestamp="2015-12-07T21:54:18Z">
    BlueKnight
  </metadata>
  <metadata tag="submitter" timestamp="2016-12-02T13:32:55Z">whissi</metadata>
</glsa>