Security Bulletin: UPDATE: Vulnerabilities in Bash affect AIX Toolbox for Linux Applications (CVE-2014-6271, CVE-2014-6277, CVE-2014-6278, CVE-2014-7169, CVE-2014-7186, and CVE-2014-7187)

Summary

Bash vulnerabilities were disclosed in September 2014. These vulnerabilities have been referred to as “Bash Bug” or “Shellshock”. Bash is optionally available via the AIX Toolbox for Linux Applications web download: http://www.ibm.com/systems/power/software/aix/linux/

If you have bash installed, read further below for Remediation/Fixes.

UPDATE: Cumulative Fixes provided to include four new CVEs: CVE-2014-6277, CVE-2014-6278, CVE-2014-7186, and CVE-2014-7187.

Vulnerability Details

CVE-ID: CVE-2014-6271

DESCRIPTION: GNU Bash could allow a remote attacker to execute arbitrary commands on the system, caused by an error when evaluating specially-crafted environment variables passed to it by the bash functionality. An attacker could exploit this vulnerability to write to files and execute arbitrary commands on the system.

CVSS Base Score: 10.0
CVSS Temporal Score: See <http://xforce.iss.net/xforce/xfdb/96153&gt; for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:N/AC:L/Au:N/C:C/I:C/A:C)

CVE-2014-6277

DESCRIPTION: GNU Bash could allow a remote attacker to execute arbitrary code on the system, caused by an incomplete fix related to the failure to properly parse function definitions in the values of environment variables. An attacker could exploit this vulnerability using attack vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server to execute arbitrary code on the system or cause a denial of service.

CVSS Base Score: 10.0
CVSS Temporal Score: See <http://xforce.iss.net/xforce/xfdb/96686&gt; for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:N/AC:L/Au:N/C:C/I:C/A:C)

CVE-2014-6278

DESCRIPTION: GNU Bash could allow a remote attacker to execute arbitrary code on the system, caused by an incomplete fix related to the parsing of user scripts. An attacker could exploit this vulnerability to execute arbitrary code on the system or cause a denial of service.

CVSS Base Score: 10.0
CVSS Temporal Score: See <http://xforce.iss.net/xforce/xfdb/96687&gt; for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:N/AC:L/Au:N/C:C/I:C/A:C)

CVE-ID: CVE-2014-7169

DESCRIPTION: GNU Bash could allow a remote attacker to execute arbitrary commands on the system, caused by an incomplete fix related to malformed function definitions in the values of environment variables. An attacker could exploit this vulnerability using attack vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server to write to files and execute arbitrary commands on the system.

CVSS Base Score: 10.0
CVSS Temporal Score: See <http://xforce.iss.net/xforce/xfdb/96209&gt; for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:N/AC:L/Au:N/C:C/I:C/A:C)

CVE-2014-7186
Description: GNU Bash could allow a local attacker to execute arbitrary code on the system, caused by an out-of-bounds memory access while handling redir_stack. An attacker could exploit this vulnerability to execute arbitrary code on the system or cause a denial of service.

CVSS Base Score: 4.6
CVSS Temporal Score: See <http://xforce.iss.net/xforce/xfdb/96237&gt; for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:L/AC:L/Au:N/C:P/I:P/A:P)

CVE-2014-7187
GNU Bash could allow a local attacker to execute arbitrary code on the system, caused by an off-by-one-error when handling deeply nested flow control constructs. An attacker could exploit this vulnerability to execute arbitrary code on the system or cause a denial of service.

CVSS Base Score: 4.6
CVSS Temporal Score: See <http://xforce.iss.net/xforce/xfdb/96238&gt; for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:L/AC:L/Au:N/C:P/I:P/A:P)

Affected Products and Versions

Toolbox for Linux Applications: bash. Affected version: 4.2-2 and lower

Remediation/Fixes

Command to verify vulnerability:
“rpm -q bash”
Result: If this output shows “bash-4.2-2” (or any number lower than 4.2), then you are vulnerable.

If you are vulnerable:
Install bash-4.2-3 (the “-3” is revision #3, which is the update that includes the fixes).

Download link for AIX 6.1 and above:
<ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/RPMS/ppc/bash/bash-4.2-3.aix6.1.ppc.rpm&gt;
Optional documentation download:
<ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/RPMS/ppc/bash/bash-doc-4.2-2.aix6.1.ppc.rpm&gt;

Install:
As root, execute the command: “rpm -hUv bash-4.2-3.aix6.1.ppc.rpm”

Optionally install documentation:
“rpm -hUv bash-4.2-3.aix6.1.ppc.rpm bash-doc-4.2-2.aix6.1.ppc.rpm”

Download link for AIX 5.3:
<ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/RPMS/ppc/bash/bash-4.2-3.aix5.3.ppc.rpm&gt;
Optional documentation download:
<ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/RPMS/ppc/bash/bash-doc-4.2-2.aix5.3.ppc.rpm&gt;

Install:
As root, execute the command: "rpm -hUv bash-4.2-3.aix5.3.ppc.rpm

Optionally install documentation:
“rpm -hUv bash-4.2-3.aix5.3.ppc.rpm bash-doc-4.2-2.aix5.3.ppc.rpm”

IBM recommends that you review your entire environment to identify vulnerable releases of Bash including other Operating Systems and take appropriate mitigation and remediation actions. Please contact your respective Operating System provider for more information.

Workarounds and Mitigations

None needed