glsa-200504-06.xml


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<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet href="/xsl/glsa.xsl" type="text/xsl"?>
<?xml-stylesheet href="/xsl/guide.xsl" type="text/xsl"?>
<!DOCTYPE glsa SYSTEM "http://www.gentoo.org/dtd/glsa.dtd">

<glsa id="200504-06">
  <title>sharutils: Insecure temporary file creation</title>
  <synopsis>
    The unshar utility is vulnerable to symlink attacks, potentially allowing a
    local user to overwrite arbitrary files.
  </synopsis>
  <product type="ebuild">sharutils</product>
  <announced>April 06, 2005</announced>
  <revised>April 06, 2005: 01</revised>
  <bug>87939</bug>
  <access>local</access>
  <affected>
    <package name="app-arch/sharutils" auto="yes" arch="*">
      <unaffected range="ge">4.2.1-r11</unaffected>
      <vulnerable range="lt">4.2.1-r11</vulnerable>
    </package>
  </affected>
  <background>
    <p>
    sharutils is a collection of tools to deal with shar archives.
    </p>
  </background>
  <description>
    <p>
    Joey Hess has discovered that the program unshar, which is a part
    of sharutils, creates temporary files in a world-writable directory
    with predictable names.
    </p>
  </description>
  <impact type="normal">
    <p>
    A local attacker could create symbolic links in the temporary
    files directory, pointing to a valid file somewhere on the filesystem.
    When unshar is executed, this would result in the file being
    overwritten with the rights of the user running the utility, which
    could be the root user.
    </p>
  </impact>
  <workaround>
    <p>
    There is no known workaround at this time.
    </p>
  </workaround>
  <resolution>
    <p>
    All sharutils users should upgrade to the latest version:
    </p>
    <code>
    # emerge --sync
    # emerge --ask --oneshot --verbose &quot;&gt;=app-arch/sharutils-4.2.1-r11&quot;</code>
  </resolution>
  <references>
    <uri link="http://www.ubuntulinux.org/support/documentation/usn/usn-104-1">Ubuntu Advisory</uri>
  </references>
  <metadata tag="requester" timestamp="Tue,  5 Apr 2005 07:42:03 +0000">
    koon
  </metadata>
  <metadata tag="submitter" timestamp="Tue,  5 Apr 2005 13:07:06 +0000">
    lewk
  </metadata>
  <metadata tag="bugReady" timestamp="Wed,  6 Apr 2005 20:15:09 +0000">
    lewk
  </metadata>
</glsa>