[LACNIC/Seguridad] Fwd: TA14-268A: GNU Bourne Again Shell (Bash) ‘Shellshock’ Vulnerability (CVE-2014-6271,CVE-2014-7169)

Vie Sep 26 09:33:24 BRT 2014

Hernán:

¿no están mal el tipo de comillas en la primera parte del codigo del seteo de la variable? .... deberian ser comillas simples y no dobles.

Saludos

Ing. Jose Luis Gaspoz
Internet Services S.A.
Tel: 0342-4565118
Cel: 342-5008523

From: Herman Mereles 
Sent: Thursday, September 25, 2014 5:32 PM
To: Lista para discusion de seguridad en redes y sistemas informaticos de la region 
Subject: Re: [LACNIC/Seguridad] Fwd: TA14-268A: GNU Bourne Again Shell (Bash) ‘Shellshock’ Vulnerability (CVE-2014-6271,CVE-2014-7169)

Raúl, compañeros,

Este es un boletín que nosotros hemos redactado,

Saludos
---

El 25/09/14 a las 16:19, Raul Cabrera escibió:

  Del Blog Schneier on Security:

  “Nasty Vulnerability found in Bash” ( https://www.schneier.com/blog/archives/2014/09/nasty_vulnerabi.html )

  Saludos cordiales.

  RAUL EDUARDO CABRERA

  De: Seguridad [mailto:seguridad-bounces en lacnic.net] En nombre de Fernando Gont
  Enviado el: jueves, 25 de septiembre de 2014 04:51 p.m.
  Para: Lista para discusión de seguridad en redes y sistemas informaticos de la región
  Asunto: [LACNIC/Seguridad] Fwd: TA14-268A: GNU Bourne Again Shell (Bash) ‘Shellshock’ Vulnerability (CVE-2014-6271,CVE-2014-7169)

  FYI

  -------- Forwarded Message -------- 

        Subject: 
       TA14-268A: GNU Bourne Again Shell (Bash) ‘Shellshock’ Vulnerability (CVE-2014-6271,CVE-2014-7169)

        Date: 
       Thu, 25 Sep 2014 14:10:57 -0500

        From: 
       US-CERT mailto:US-CERT en ncas.us-cert.gov

        Reply-To: 
       US-CERT en ncas.us-cert.gov

        To: 
       fernando en gont.com.ar

        National Cyber Awareness System:

        TA14-268A: GNU Bourne Again Shell (Bash) ‘Shellshock’ Vulnerability (CVE-2014-6271,CVE-2014-7169)

        09/25/2014 12:56 PM EDT

        Original release date: September 25, 2014

        Systems Affected
          a.. GNU Bash through 4.3. 
          b.. Linux, BSD, and UNIX distributions including but not limited to: 
            a.. CentOS 5 through 7 
            b.. Debian 
            c.. Mac OS X 
            d.. Red Hat Enterprise Linux 4 through 7 
            e.. Ubuntu 10.04 LTS, 12.04 LTS, and 14.04 LTS 
        Overview
        A critical vulnerability has been reported in the GNU Bourne Again Shell (Bash), the common command-line shell used in most Linux/UNIX operating systems and Apple’s Mac OS X. The flaw could allow an attacker to remotely execute shell commands by attaching malicious code in environment variables used by the operating system [1]. The United States Department of Homeland Security (DHS) is releasing this Technical Alert to provide further information about the GNU Bash vulnerability.

        Description
        GNU Bash versions 1.14 through 4.3 contain a flaw that processes commands placed after function definitions in the added environment variable, allowing remote attackers to execute arbitrary code via a crafted environment which enables network-based exploitation. [2, 3]

        Critical instances where the vulnerability may be exposed include: [4, 5]

          a.. Apache HTTP Server using mod_cgi or mod_cgid scripts either written in bash, or spawn subshells. 
          b.. Override or Bypass ForceCommand feature in OpenSSH sshd and limited protection for some Git and Subversion deployments used to restrict shells and allows arbitrary command execution capabilities. 
          c.. Allow arbitrary commands to run on a DHCP client machine, various Daemons and SUID/privileged programs. 
          d.. Exploit servers and other Unix and Linux devices via Web requests, secure shell, telnet sessions, or other programs that use Bash to execute scripts. 
        Impact
        This vulnerability is classified by industry standards as “High” impact with CVSS Impact Subscore 10 and “Low” on complexity, which means it takes little skill to perform. This flaw allows attackers to provide specially crafted environment variables containing arbitrary commands that can be executed on vulnerable systems. It is especially dangerous because of the prevalent use of the Bash shell and its ability to be called by an application in numerous ways.

        Solution
        Patches have been released to fix this vulnerability by major Linux vendors for affected versions. Solutions for CVE-2014-6271 do not completely resolve the vulnerability. It is advised to install existing patches and pay attention for updated patches to address CVE-2014-7169.

        Many UNIX-like operating systems, including Linux distributions, BSD variants, and Apple Mac OS X include Bash and are likely to be affected. Contact your vendor for updated information. A list of vendors can be found in CERT Vulnerability Note VU#252743 [6].

        US-CERT recommends system administrators review the vendor patches and the NIST Vulnerability Summary for CVE-2014-7169, to mitigate damage caused by the exploit.

        References
          a.. Ars Technica, Bug in Bash shell creates big security hole on anything with *nix in it; 
          b.. DHS NCSD; Vulnerability Summary for CVE-2014-6271 
          c.. DHS NCSD; Vulnerability Summary for CVE-2014-7169 
          d.. Red Hat, CVE-2014-6271 
          e.. Red Hat, Bash specially-crafted environment variables code injection attack 
          f.. CERT Vulnerability Note VU#252743 
        Revision History
          a.. September 25, 2014 - Initial Release 

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