Vulnerabilities > CVE-2017-3878 - Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability in Cisco Nx-Os 7.0(3)I3(0.170)

047910
CVSS 5.3 - MEDIUM
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
NONE
Availability impact
LOW
network
low complexity
cisco
CWE-119
nessus
NVD
Published: 2017-03-17
Updated: 2024-11-21

Summary

A Denial of Service vulnerability in the Telnet remote login functionality of Cisco NX-OS Software running on Cisco Nexus 9000 Series Switches could allow an unauthenticated, remote attacker to cause a Telnet process used for login to terminate unexpectedly and the login attempt to fail. There is no impact to user traffic flowing through the device. Affected Products: This vulnerability affects Cisco Nexus 9000 Series Switches that are running Cisco NX-OS Software and are configured to allow remote Telnet connections to the device. More Information: CSCux46778. Known Affected Releases: 7.0(3)I3(0.170). Known Fixed Releases: 7.0(3)I3(1) 7.0(3)I3(0.257) 7.0(3)I3(0.255) 7.0(3)I2(2e) 7.0(3)F1(1.22) 7.0(3)F1(1).

Vulnerable Configurations

Part Description Count
OS
Cisco
1
Hardware
Cisco
19

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.
  • Overflow Buffers
    Buffer Overflow attacks target improper or missing bounds checking on buffer operations, typically triggered by input injected by an attacker. As a consequence, an attacker is able to write past the boundaries of allocated buffer regions in memory, causing a program crash or potentially redirection of execution as per the attackers' choice.
  • Client-side Injection-induced Buffer Overflow
    This type of attack exploits a buffer overflow vulnerability in targeted client software through injection of malicious content from a custom-built hostile service.
  • Filter Failure through Buffer Overflow
    In this attack, the idea is to cause an active filter to fail by causing an oversized transaction. An attacker may try to feed overly long input strings to the program in an attempt to overwhelm the filter (by causing a buffer overflow) and hoping that the filter does not fail securely (i.e. the user input is let into the system unfiltered).
  • MIME Conversion
    An attacker exploits a weakness in the MIME conversion routine to cause a buffer overflow and gain control over the mail server machine. The MIME system is designed to allow various different information formats to be interpreted and sent via e-mail. Attack points exist when data are converted to MIME compatible format and back.

Nessus

NASL familyCISCO
NASL idCISCO-SA-20170315-NSS-NXOS.NASL
descriptionAccording to its version and configuration, the Cisco NX-OS software running on the remote device is affected by a denial of service vulnerability in the Telnet remote login functionality due to improper validation of Telnet packet headers. An unauthenticated, remote attacker can exploit this, via specially crafted Telnet packets, to cause the Telnet process to restart.
last seen2020-06-01
modified2020-06-02
plugin id99371
published2017-04-14
reporterThis script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/99371
titleCisco NX-OS Telnet Packet Header Handling Remote DoS (cisco-sa-20170315-nss)
code
#TRUSTED 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
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(99371);
  script_version("1.9");
  script_cvs_date("Date: 2019/11/13");

  script_cve_id("CVE-2017-3878");
  script_bugtraq_id(96927);
  script_xref(name:"CISCO-BUG-ID", value:"CSCux46778");
  script_xref(name:"IAVA", value:"2017-A-0096");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20170315-nss");

  script_name(english:"Cisco NX-OS Telnet Packet Header Handling Remote DoS (cisco-sa-20170315-nss)");
  script_summary(english:"Checks the NX-OS 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 version and configuration, the Cisco NX-OS software
running on the remote device is affected by a denial of service
vulnerability in the Telnet remote login functionality due to improper
validation of Telnet packet headers. An unauthenticated, remote
attacker can exploit this, via specially crafted Telnet packets, to
cause the Telnet process to restart.");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170315-nss
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?2ea47371");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bug ID
CSCux46778.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P");
  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:L");
  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:"2017/03/15");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/03/15");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/04/14");

  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:nx-os");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("cisco_nxos_version.nasl");
  script_require_keys("Host/Cisco/NX-OS/Version", "Host/Cisco/NX-OS/Device", "Host/Cisco/NX-OS/Model");

  exit(0);
}

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

device  = get_kb_item_or_exit("Host/Cisco/NX-OS/Device");
model   = get_kb_item_or_exit("Host/Cisco/NX-OS/Model");
version = get_kb_item_or_exit("Host/Cisco/NX-OS/Version");

# Only affects Nexus
if (device != 'Nexus')
  audit(AUDIT_HOST_NOT, "affected");

flag = 0;
cbid = FALSE;

########################################
# Model 9k
########################################
if (model =~ "^9[0-9][0-9][0-9]([^0-9]|$)")
{
  if(version == "7.0(3)I3(0.170)") flag = TRUE;
  cbid = "CSCux46778";
}

if (flag && get_kb_item("Host/local_checks_enabled"))
{
  flag = FALSE;

# Check for telnet feature
  buf = cisco_command_kb_item("Host/Cisco/Config/show_running-config", "show running-config");
  if (check_cisco_result(buf))
  {
    if (preg(multiline:TRUE, pattern:"^(\s+)?feature telnet", string:buf))
    flag = TRUE;
  }
  else if (cisco_needs_enable(buf)) override = TRUE;
}

if (flag || override)
{
  security_report_cisco(
    port     : 0,
    severity : SECURITY_WARNING,
    override : override,
    version  : version,
    bug_id   : cbid
  );
}
else audit(AUDIT_HOST_NOT, "affected");

References