[USN-3534-1] GNU C Library vulnerabilities

[Chris Coulson]

==========================================================================
Ubuntu Security Notice USN-3534-1
January 17, 2018

eglibc, glibc vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 17.10
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in the GNU C library.

Software Description:
- glibc: GNU C Library
- eglibc: GNU C Library

Details:

It was discovered that the GNU C library did not properly handle all of
the possible return values from the kernel getcwd(2) syscall. A local
attacker could potentially exploit this to execute arbitrary code in setuid
programs and gain administrative privileges. (CVE-2018-1000001)

A memory leak was discovered in the _dl_init_paths() function in the GNU
C library dynamic loader. A local attacker could potentially exploit this
with a specially crafted value in the LD_HWCAP_MASK environment variable,
in combination with CVE-2017-1000409 and another vulnerability on a system
with hardlink protections disabled, in order to gain administrative
privileges. (CVE-2017-1000408)

A heap-based buffer overflow was discovered in the _dl_init_paths()
function in the GNU C library dynamic loader. A local attacker could
potentially exploit this with a specially crafted value in the
LD_LIBRARY_PATH environment variable, in combination with CVE-2017-1000408
and another vulnerability on a system with hardlink protections disabled,
in order to gain administrative privileges. (CVE-2017-1000409)

An off-by-one error leading to a heap-based buffer overflow was discovered
in the GNU C library glob() implementation. An attacker could potentially
exploit this to cause a denial of service or execute arbitrary code via a
maliciously crafted pattern. (CVE-2017-15670)

A heap-based buffer overflow was discovered during unescaping of user names
with the ~ operator in the GNU C library glob() implementation. An attacker
could potentially exploit this to cause a denial of service or execute
arbitrary code via a maliciously crafted pattern. (CVE-2017-15804)

It was discovered that the GNU C library dynamic loader mishandles RPATH
and RUNPATH containing $ORIGIN for privileged (setuid or AT_SECURE)
programs. A local attacker could potentially exploit this by providing a
specially crafted library in the current working directory in order to
gain administrative privileges. (CVE-2017-16997)

It was discovered that the GNU C library malloc() implementation could
return a memory block that is too small if an attempt is made to allocate
an object whose size is close to SIZE_MAX, resulting in a heap-based
overflow. An attacker could potentially exploit this to cause a denial of
service or execute arbitrary code. This issue only affected Ubuntu 17.10.
(CVE-2017-17426)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 17.10:
  libc6                           2.26-0ubuntu2.1

Ubuntu 16.04 LTS:
  libc6                           2.23-0ubuntu10

Ubuntu 14.04 LTS:
  libc6                           2.19-0ubuntu6.14

After a standard system update you need to reboot your computer to make
all the necessary changes.

References:
  https://www.ubuntu.com/usn/usn-3534-1
  CVE-2017-1000408, CVE-2017-1000409, CVE-2017-15670, CVE-2017-15804,
  CVE-2017-16997, CVE-2017-17426, CVE-2018-1000001

Package Information:
  https://launchpad.net/ubuntu/+source/glibc/2.26-0ubuntu2.1
  https://launchpad.net/ubuntu/+source/glibc/2.23-0ubuntu10
  https://launchpad.net/ubuntu/+source/eglibc/2.19-0ubuntu6.14


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