Vulnerabilities > CVE-2016-6441 - Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability in Cisco IOS XE

047910
CVSS 9.8 - CRITICAL
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
HIGH
Integrity impact
HIGH
Availability impact
HIGH
network
low complexity
cisco
CWE-119
critical
nessus
NVD
Published: 2016-11-03
Updated: 2024-11-21

Summary

A vulnerability in the Transaction Language 1 (TL1) code of Cisco ASR 900 Series routers could allow an unauthenticated, remote attacker to cause a reload of, or remotely execute code on, the affected system. This vulnerability affects Cisco ASR 900 Series Aggregation Services Routers (ASR902, ASR903, and ASR907) that are running the following releases of Cisco IOS XE Software: 3.17.0S 3.17.1S 3.17.2S 3.18.0S 3.18.1S. More Information: CSCuy15175. Known Affected Releases: 15.6(1)S 15.6(2)S. Known Fixed Releases: 15.6(1)S2.12 15.6(1.17)S0.41 15.6(1.17)SP 15.6(2)SP 16.4(0.183) 16.5(0.10).

Vulnerable Configurations

Part Description Count
OS
Cisco
7

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-20161102-TL1.NASL
descriptionAccording to its self-reported version and model, the Cisco IOS XE software running on the remote ASR device is affected by a remote code execution vulnerability in the Transaction Language 1 (TL1) code due to an overflow condition caused by improper bounds checking on certain input when handling TL1 requests. An unauthenticated, remote attacker can exploit this, via a specially crafted request to the TL1 port, to cause a denial of service condition or the execution of arbitrary code.
last seen2020-05-09
modified2016-11-10
plugin id94680
published2016-11-10
reporterThis script is Copyright (C) 2016-2020 Tenable Network Security, Inc.
sourcehttps://www.tenable.com/plugins/nessus/94680
titleCisco IOS XE TL1 Request Handling RCE (cisco-sa-20161102-tl1)
code
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(94680);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/05/08");

  script_cve_id("CVE-2016-6441");
  script_bugtraq_id(94072);
  script_xref(name:"CISCO-SA", value:"cisco-sa-20161102-tl1");
  script_xref(name:"IAVA", value:"2017-A-0002-S");
  script_xref(name:"CISCO-BUG-ID", value:"CSCuy15175");

  script_name(english:"Cisco IOS XE TL1 Request Handling RCE (cisco-sa-20161102-tl1)");
  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 model, the Cisco IOS XE
software running on the remote ASR device is affected by a remote code
execution vulnerability in the Transaction Language 1 (TL1) code due
to an overflow condition caused by improper bounds checking on certain
input when handling TL1 requests. An unauthenticated, remote attacker
can exploit this, via a specially crafted request to the TL1 port, to
cause a denial of service condition or the execution of arbitrary
code.");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161102-tl1
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?1cb66121");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCuy15175");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bug ID
CSCuy15175. Alternatively, as a mitigation, deploy infrastructure
access control lists (iACLs) to prevent TL1 packets from reaching the
device.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/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:H/I:H/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:"exploit_available", value:"false");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2016/11/02");
  script_set_attribute(attribute:"patch_publication_date", value:"2016/11/02");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/11/10");

  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2016-2020 Tenable Network Security, Inc.");
  script_family(english:"CISCO");

  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");

# Check model
# Affected: ASR902, ASR903, ASR907
model = get_kb_item("CISCO/model");
if(empty_or_null(model)) model = get_kb_item_or_exit("Host/Cisco/IOS-XE/Model");
if(model && model !~ "^ASR90[237]([^0-9]|$)") audit(AUDIT_DEVICE_NOT_VULN, model);

app = "Cisco IOS XE";
cbi = "CSCuy15175";
fix = NULL;

if (
  ver == "3.17.0S" ||
  ver == "3.17.1S" ||
  ver == "3.17.2S"
)
  fix = '3.17.3S';
if (
  ver == "3.18.0S" ||
  ver == "3.18.1S"
)
  fix = '3.18.2S';

if(!empty_or_null(fix))
{

  security_report_cisco(
  port     : 0,
  severity : SECURITY_HOLE,
  version  : ver,
  bug_id   : cbi,
  fix      : fix
  );

}
else audit(AUDIT_HOST_NOT, "affected");

References