Vulnerabilities > CVE-2016-1478 - Improper Input Validation vulnerability in Cisco IOS

047910
CVSS 7.5 - HIGH
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
NONE
Availability impact
HIGH
network
low complexity
cisco
CWE-20
nessus
NVD
Published: 2016-08-08
Updated: 2017-08-16

Summary

Cisco IOS 15.5(3)S3, 15.6(1)S2, 15.6(2)S1, and 15.6(2)T1 does not properly dequeue invalid NTP packets, which allows remote attackers to cause a denial of service (interface wedge) by sending many crafted NTP packets, aka Bug ID CSCva35619.

Vulnerable Configurations

Part Description Count
OS
Cisco
4

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Buffer Overflow via Environment Variables
    This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
  • Server Side Include (SSI) Injection
    An attacker can use Server Side Include (SSI) Injection to send code to a web application that then gets executed by the web server. Doing so enables the attacker to achieve similar results to Cross Site Scripting, viz., arbitrary code execution and information disclosure, albeit on a more limited scale, since the SSI directives are nowhere near as powerful as a full-fledged scripting language. Nonetheless, the attacker can conveniently gain access to sensitive files, such as password files, and execute shell commands.
  • Cross Zone Scripting
    An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security. In a zone-based model, pages belong to one of a set of zones corresponding to the level of privilege assigned to that page. Pages in an untrusted zone would have a lesser level of access to the system and/or be restricted in the types of executable content it was allowed to invoke. In a cross-zone scripting attack, a page that should be assigned to a less privileged zone is granted the privileges of a more trusted zone. This can be accomplished by exploiting bugs in the browser, exploiting incorrect configuration in the zone controls, through a cross-site scripting attack that causes the attackers' content to be treated as coming from a more trusted page, or by leveraging some piece of system functionality that is accessible from both the trusted and less trusted zone. This attack differs from "Restful Privilege Escalation" in that the latter correlates to the inadequate securing of RESTful access methods (such as HTTP DELETE) on the server, while cross-zone scripting attacks the concept of security zones as implemented by a browser.
  • Cross Site Scripting through Log Files
    An attacker may leverage a system weakness where logs are susceptible to log injection to insert scripts into the system's logs. If these logs are later viewed by an administrator through a thin administrative interface and the log data is not properly HTML encoded before being written to the page, the attackers' scripts stored in the log will be executed in the administrative interface with potentially serious consequences. This attack pattern is really a combination of two other attack patterns: log injection and stored cross site scripting.
  • Command Line Execution through SQL Injection
    An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.

Nessus

  • NASL familyCISCO
    NASL idCISCO-SA-20160804-WEDGE-IOS.NASL
    descriptionAccording to its self-reported version and configuration, the Cisco IOS software running on the remote device is affected by a denial of service vulnerability due to insufficient checks on clearing invalid Network Time Protocol (NTP) packets from the interface queue. An unauthenticated, remote attacker can exploit this to cause an interface wedge, resulting in a denial of service condition.
    last seen2020-06-01
    modified2020-06-02
    plugin id93192
    published2016-08-29
    reporterThis script is Copyright (C) 2016-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/93192
    titleCisco IOS NTP Packet Handling Remote DoS (cisco-sa-20160804-wedge)
    code
    #TRUSTED 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
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(93192);
  script_version("1.9");
  script_cvs_date("Date: 2019/11/14");

  script_cve_id("CVE-2016-1478");
  script_bugtraq_id(92317);
  script_xref(name:"CISCO-BUG-ID", value:"CSCva35619");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20160804-wedge");

  script_name(english:"Cisco IOS NTP Packet Handling Remote DoS (cisco-sa-20160804-wedge)");
  script_summary(english:"Checks the IOS version.");

  script_set_attribute(attribute:"synopsis", value:
"The remote device is missing a vendor-supplied security patch.");
  script_set_attribute(attribute:"description", value:
"According to its self-reported version and configuration, the Cisco
IOS software running on the remote device is affected by a denial of
service vulnerability due to insufficient checks on clearing invalid
Network Time Protocol (NTP) packets from the interface queue. An
unauthenticated, remote attacker can exploit this to cause an
interface wedge, resulting in a denial of service condition.");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160804-wedge
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?57eccdac");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bug ID
CSCva35619.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C");
  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:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"vuln_publication_date", value:"2016/08/04");
  script_set_attribute(attribute:"patch_publication_date", value:"2016/08/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/08/29");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:ios");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"CISCO");

  script_copyright(english:"This script is Copyright (C) 2016-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("cisco_ios_version.nasl");
  script_require_keys("Host/Cisco/IOS/Version");

  exit(0);
}

include("audit.inc");
include("cisco_func.inc");
include("cisco_kb_cmd_func.inc");

flag = 0;
override = 0;

ver = get_kb_item_or_exit("Host/Cisco/IOS/Version");

# Check for vuln version
if ( ver == '15.5(3)S3' ) flag++;
if ( ver == '15.6(1)S2' ) flag++;
if ( ver == '15.6(2)S1' ) flag++;
if ( ver == '15.6(2)T1' ) flag++;

# NTP check
if (flag && get_kb_item("Host/local_checks_enabled"))
{
  buf = cisco_command_kb_item("Host/Cisco/Config/show_ntp_status", "show ntp status");

  # Check for traces of ntp
  if (check_cisco_result(buf))
  {
    if (
      "%NTP is not enabled." >< buf &&
      "system poll" >!< buf &&
      "Clock is" >!< buf
    ) audit(AUDIT_HOST_NOT, "affected because NTP is not enabled");
  }
  else if (cisco_needs_enable(buf)) override = 1;
}

if (flag)
{
  security_report_cisco(
    port     : 0,
    severity : SECURITY_HOLE,
    override : override,
    version  : ver,
    bug_id   : "CSCva35619",
    cmds     : make_list("show ntp status")
  );
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");
  • NASL familyCISCO
    NASL idCISCO-SA-20160804-WEDGE-IOSXE.NASL
    descriptionAccording to its self-reported version and configuration, the Cisco IOS XE software running on the remote device is affected by a denial of service vulnerability due to insufficient checks on clearing invalid Network Time Protocol (NTP) packets from the interface queue. An unauthenticated, remote attacker can exploit this to cause an interface wedge, resulting in a denial of service condition.
    last seen2020-06-01
    modified2020-06-02
    plugin id93193
    published2016-08-29
    reporterThis script is Copyright (C) 2016-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/93193
    titleCisco IOS XE NTP Packet Handling Remote DoS (cisco-sa-20160804-wedge)
    code
    #TRUSTED 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
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(93193);
  script_version("1.9");
  script_cvs_date("Date: 2019/11/14");

  script_cve_id("CVE-2016-1478");
  script_bugtraq_id(92317);
  script_xref(name:"CISCO-BUG-ID", value:"CSCva35619");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20160804-wedge");

  script_name(english:"Cisco IOS XE NTP Packet Handling Remote DoS (cisco-sa-20160804-wedge)");
  script_summary(english:"Checks the IOS XE version.");

  script_set_attribute(attribute:"synopsis", value:
"The remote device is missing a vendor-supplied security patch.");
  script_set_attribute(attribute:"description", value:
"According to its self-reported version and configuration, the Cisco
IOS XE software running on the remote device is affected by a denial
of service vulnerability due to insufficient checks on clearing
invalid Network Time Protocol (NTP) packets from the interface queue.
An unauthenticated, remote attacker can exploit this to cause an
interface wedge, resulting in a denial of service condition.");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160804-wedge
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?57eccdac");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bug ID
CSCva35619.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C");
  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:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"vuln_publication_date", value:"2016/08/04");
  script_set_attribute(attribute:"patch_publication_date", value:"2016/08/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/08/29");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:ios_xe");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"CISCO");

  script_copyright(english:"This script is Copyright (C) 2016-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("cisco_ios_xe_version.nasl");
  script_require_keys("Host/Cisco/IOS-XE/Version");

  exit(0);
}

include("audit.inc");
include("cisco_func.inc");
include("cisco_kb_cmd_func.inc");

ver = get_kb_item_or_exit("Host/Cisco/IOS-XE/Version");

flag = 0;
override = 0;

# Check for vuln version
if ( ver == '3.16.3S' ) flag++;
if ( ver == '3.17.2S' ) flag++;
if ( ver == '3.18.1S' ) flag++;
#if ( ver == '?.?.?' ) flag++; # 15.6(2)T1 IOS == ? IOS XE

# NTP check
if (flag && get_kb_item("Host/local_checks_enabled"))
{
  buf = cisco_command_kb_item("Host/Cisco/Config/show_ntp_status", "show ntp status");
  # Check for traces of ntp
  if (check_cisco_result(buf))
  {
    if (
      "%NTP is not enabled." >< buf &&
      "system poll" >!< buf &&
      "Clock is" >!< buf
    ) audit(AUDIT_HOST_NOT, "affected because NTP is not enabled");
  }
  else if (cisco_needs_enable(buf)) override = 1;
}

if (flag)
{
  security_report_cisco(
    port     : 0,
    severity : SECURITY_HOLE,
    override : override,
    version  : ver,
    bug_id   : "CSCva35619",
    cmds     : make_list("show ntp status")
  );
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");

References