Vulnerabilities > CVE-2014-3556 - Command Injection vulnerability in F5 Nginx

047910
CVSS 6.8 - MEDIUM
Attack vector
NETWORK
Attack complexity
MEDIUM
Privileges required
NONE
Confidentiality impact
PARTIAL
Integrity impact
PARTIAL
Availability impact
PARTIAL
network
f5
CWE-77
nessus

Summary

The STARTTLS implementation in mail/ngx_mail_smtp_handler.c in the SMTP proxy in nginx 1.5.x and 1.6.x before 1.6.1 and 1.7.x before 1.7.4 does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted SMTP sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411.

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Cause Web Server Misclassification
    An attack of this type exploits a Web server's decision to take action based on filename or file extension. Because different file types are handled by different server processes, misclassification may force the Web server to take unexpected action, or expected actions in an unexpected sequence. This may cause the server to exhaust resources, supply debug or system data to the attacker, or bind an attacker to a remote process. This type of vulnerability has been found in many widely used servers including IIS, Lotus Domino, and Orion. The attacker's job in this case is straightforward, standard communication protocols and methods are used and are generally appended with malicious information at the tail end of an otherwise legitimate request. The attack payload varies, but it could be special characters like a period or simply appending a tag that has a special meaning for operations on the server side like .jsp for a java application server. The essence of this attack is that the attacker deceives the server into executing functionality based on the name of the request, i.e. login.jsp, not the contents.
  • LDAP Injection
    An attacker manipulates or crafts an LDAP query for the purpose of undermining the security of the target. Some applications use user input to create LDAP queries that are processed by an LDAP server. For example, a user might provide their username during authentication and the username might be inserted in an LDAP query during the authentication process. An attacker could use this input to inject additional commands into an LDAP query that could disclose sensitive information. For example, entering a * in the aforementioned query might return information about all users on the system. This attack is very similar to an SQL injection attack in that it manipulates a query to gather additional information or coerce a particular return value.
  • Command Delimiters
    An attack of this type exploits a programs' vulnerabilities that allows an attacker's commands to be concatenated onto a legitimate command with the intent of targeting other resources such as the file system or database. The system that uses a filter or a blacklist input validation, as opposed to whitelist validation is vulnerable to an attacker who predicts delimiters (or combinations of delimiters) not present in the filter or blacklist. As with other injection attacks, the attacker uses the command delimiter payload as an entry point to tunnel through the application and activate additional attacks through SQL queries, shell commands, network scanning, and so on.
  • File System Function Injection, Content Based
    An attack of this type exploits the host's trust in executing remote content including binary files. The files are poisoned with a malicious payload (targeting the file systems accessible by the target software) by the attacker and may be passed through standard channels such as via email, and standard web content like PDF and multimedia files. The attacker exploits known vulnerabilities or handling routines in the target processes. Vulnerabilities of this type have been found in a wide variety of commercial applications from Microsoft Office to Adobe Acrobat and Apple Safari web browser. When the attacker knows the standard handling routines and can identify vulnerabilities and entry points they can be exploited by otherwise seemingly normal content. Once the attack is executed, the attackers' program can access relative directories such as C:\Program Files or other standard system directories to launch further attacks. In a worst case scenario, these programs are combined with other propagation logic and work as a virus.
  • Exploiting Multiple Input Interpretation Layers
    An attacker supplies the target software with input data that contains sequences of special characters designed to bypass input validation logic. This exploit relies on the target making multiples passes over the input data and processing a "layer" of special characters with each pass. In this manner, the attacker can disguise input that would otherwise be rejected as invalid by concealing it with layers of special/escape characters that are stripped off by subsequent processing steps. The goal is to first discover cases where the input validation layer executes before one or more parsing layers. That is, user input may go through the following logic in an application: In such cases, the attacker will need to provide input that will pass through the input validator, but after passing through parser2, will be converted into something that the input validator was supposed to stop.

Nessus

  • NASL familyWeb Servers
    NASL idNGINX_1_7_4.NASL
    descriptionAccording to the self-reported version in the server response header, the version of nginx installed on the remote host is 1.5.6 or higher, 1.6.x prior to 1.6.1, or 1.7.x prior to 1.7.4. It is, therefore, affected by a command injection vulnerability. A flaw exists in the function
    last seen2020-05-09
    modified2014-08-19
    plugin id77246
    published2014-08-19
    reporterThis script is Copyright (C) 2014-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/77246
    titlenginx < 1.6.1 / 1.7.4 SMTP STARTTLS Command Injection
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    
    include('compat.inc');
    
    if (description)
    {
      script_id(77246);
      script_version("1.9");
      script_set_attribute(attribute:"plugin_modification_date", value:"2020/05/08");
    
      script_cve_id("CVE-2014-3556");
      script_bugtraq_id(69111);
    
      script_name(english:"nginx < 1.6.1 / 1.7.4 SMTP STARTTLS Command Injection");
    
      script_set_attribute(attribute:"synopsis", value:
    "The remote web server is affected by a command injection
    vulnerability.");
      script_set_attribute(attribute:"description", value:
    "According to the self-reported version in the server response header,
    the version of nginx installed on the remote host is 1.5.6 or higher,
    1.6.x prior to 1.6.1, or 1.7.x prior to 1.7.4. It is, therefore,
    affected by a command injection vulnerability.
    
    A flaw exists in the function 'ngx_mail_smtp_starttls' within the file
    'src/mail/ngx_mail_smtp_handler.c' whereby input to the STARTTLS
    command is not properly sanitized. This could allow a remote attacker
    in a privileged network position to obtain sensitive information by
    injecting commands into an SSL session.
    
    Note that this issue is exploitable only when nginx is used as an SMTP
    proxy.");
      script_set_attribute(attribute:"see_also", value:"http://nginx.org/en/security_advisories.html");
      script_set_attribute(attribute:"see_also", value:"http://mailman.nginx.org/pipermail/nginx-announce/2014/000144.html");
      script_set_attribute(attribute:"see_also", value:"http://nginx.org/download/patch.2014.starttls.txt");
      script_set_attribute(attribute:"see_also", value:"http://nginx.org/en/CHANGES");
      script_set_attribute(attribute:"see_also", value:"http://nginx.org/en/CHANGES-1.6");
      script_set_attribute(attribute:"solution", value:
    "Apply the patch manually, or upgrade to nginx 1.6.1 / 1.7.4 or later.");
      script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:N/A:N");
      script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
      script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N");
      script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
      script_set_attribute(attribute:"cvss_score_source", value:"CVE-2014-3556");
    
      script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
      script_set_attribute(attribute:"exploit_available", value:"false");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2014/08/05");
      script_set_attribute(attribute:"patch_publication_date", value:"2014/08/05");
      script_set_attribute(attribute:"plugin_publication_date", value:"2014/08/19");
    
      script_set_attribute(attribute:"plugin_type", value:"combined");
      script_set_attribute(attribute:"cpe", value:"cpe:/a:igor_sysoev:nginx");
      script_set_attribute(attribute:"agent", value:"unix");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_family(english:"Web Servers");
    
      script_copyright(english:"This script is Copyright (C) 2014-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
    
      script_dependencies("nginx_detect.nasl", "nginx_nix_installed.nbin");
      script_require_keys("installed_sw/nginx");
    
      exit(0);
    }
    
    include('http.inc');
    include('vcf.inc');
    
    appname = 'nginx';
    get_install_count(app_name:appname, exit_if_zero:TRUE);
    app_info = vcf::combined_get_app_info(app:appname);
    
    vcf::check_granularity(app_info:app_info, sig_segments:3);
    # If the detection is only remote, Detection Method won't be set, and we should require paranoia
    if (empty_or_null(app_info['Detection Method']) && report_paranoia < 2)
      audit(AUDIT_PARANOID);
    
    constraints = [
      {'min_version':'1.5.6', 'fixed_version':'1.6.1'},
      {'min_version':'1.7.0', 'fixed_version':'1.7.4'}
    ];
    vcf::check_version_and_report(app_info:app_info, constraints:constraints, severity:SECURITY_WARNING);
    
  • NASL familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_AD747A011FEE11E48FF1F0DEF16C5C1B.NASL
    descriptionThe nginx project reports : Security: pipelined commands were not discarded after STARTTLS command in SMTP proxy (CVE-2014-3556); the bug had appeared in 1.5.6.
    last seen2020-06-01
    modified2020-06-02
    plugin id77109
    published2014-08-10
    reporterThis script is Copyright (C) 2014-2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/77109
    titleFreeBSD : nginx -- inject commands into SSL session vulnerability (ad747a01-1fee-11e4-8ff1-f0def16c5c1b)
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were  
    # extracted from the FreeBSD VuXML database :
    #
    # Copyright 2003-2018 Jacques Vidrine and contributors
    #
    # Redistribution and use in source (VuXML) and 'compiled' forms (SGML,
    # HTML, PDF, PostScript, RTF and so forth) with or without modification,
    # are permitted provided that the following conditions are met:
    # 1. Redistributions of source code (VuXML) must retain the above
    #    copyright notice, this list of conditions and the following
    #    disclaimer as the first lines of this file unmodified.
    # 2. Redistributions in compiled form (transformed to other DTDs,
    #    published online in any format, converted to PDF, PostScript,
    #    RTF and other formats) must reproduce the above copyright
    #    notice, this list of conditions and the following disclaimer
    #    in the documentation and/or other materials provided with the
    #    distribution.
    # 
    # THIS DOCUMENTATION IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS"
    # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
    # THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
    # PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
    # BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
    # OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
    # OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
    # BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
    # WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
    # OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS DOCUMENTATION,
    # EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(77109);
      script_version("1.3");
      script_cvs_date("Date: 2018/11/10 11:49:44");
    
      script_cve_id("CVE-2014-3556");
    
      script_name(english:"FreeBSD : nginx -- inject commands into SSL session vulnerability (ad747a01-1fee-11e4-8ff1-f0def16c5c1b)");
      script_summary(english:"Checks for updated packages in pkg_info output");
    
      script_set_attribute(
        attribute:"synopsis", 
        value:
    "The remote FreeBSD host is missing one or more security-related
    updates."
      );
      script_set_attribute(
        attribute:"description", 
        value:
    "The nginx project reports :
    
    Security: pipelined commands were not discarded after STARTTLS command
    in SMTP proxy (CVE-2014-3556); the bug had appeared in 1.5.6."
      );
      script_set_attribute(
        attribute:"see_also",
        value:"http://mailman.nginx.org/pipermail/nginx-announce/2014/000144.html"
      );
      # https://vuxml.freebsd.org/freebsd/ad747a01-1fee-11e4-8ff1-f0def16c5c1b.html
      script_set_attribute(
        attribute:"see_also",
        value:"http://www.nessus.org/u?0afc1146"
      );
      script_set_attribute(attribute:"solution", value:"Update the affected packages.");
      script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:N/A:N");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:nginx");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:nginx-devel");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:freebsd:freebsd");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2014/08/05");
      script_set_attribute(attribute:"patch_publication_date", value:"2014/08/09");
      script_set_attribute(attribute:"plugin_publication_date", value:"2014/08/10");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2014-2018 and is owned by Tenable, Inc. or an Affiliate thereof.");
      script_family(english:"FreeBSD Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/FreeBSD/release", "Host/FreeBSD/pkg_info");
    
      exit(0);
    }
    
    
    include("audit.inc");
    include("freebsd_package.inc");
    
    
    if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
    if (!get_kb_item("Host/FreeBSD/release")) audit(AUDIT_OS_NOT, "FreeBSD");
    if (!get_kb_item("Host/FreeBSD/pkg_info")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    
    flag = 0;
    
    if (pkg_test(save_report:TRUE, pkg:"nginx>=1.6.0,2<1.6.1,2")) flag++;
    if (pkg_test(save_report:TRUE, pkg:"nginx-devel>=1.5.6<1.7.4")) flag++;
    
    if (flag)
    {
      if (report_verbosity > 0) security_warning(port:0, extra:pkg_report_get());
      else security_warning(0);
      exit(0);
    }
    else audit(AUDIT_HOST_NOT, "affected");