Vulnerabilities > CVE-2018-1352 - Use of Externally-Controlled Format String vulnerability in Fortinet Fortios 5.6.0

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
fortinet
CWE-134
critical
nessus
NVD
Published: 2019-02-08
Updated: 2019-02-08

Summary

A format string vulnerability in Fortinet FortiOS 5.6.0 allows attacker to execute unauthorized code or commands via the SSH username variable.

Vulnerable Configurations

Part Description Count
OS
Fortinet
1

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Format String Injection
    An attacker includes formatting characters in a string input field on the target application. Most applications assume that users will provide static text and may respond unpredictably to the presence of formatting character. For example, in certain functions of the C programming languages such as printf, the formatting character %s will print the contents of a memory location expecting this location to identify a string and the formatting character %n prints the number of DWORD written in the memory. An attacker can use this to read or write to memory locations or files, or simply to manipulate the value of the resulting text in unexpected ways. Reading or writing memory may result in program crashes and writing memory could result in the execution of arbitrary code if the attacker can write to the program stack.
  • String Format Overflow in syslog()
    This attack targets the format string vulnerabilities in the syslog() function. An attacker would typically inject malicious input in the format string parameter of the syslog function. This is a common problem, and many public vulnerabilities and associated exploits have been posted.

Nessus

NASL familyFirewalls
NASL idFORTIOS_FG-IR-18-018.NASL
descriptionThe version of Fortinet FortiOS running on the remote device is 5.6.0. It is, therefore, affected by a remote execution vulnerability which can be exploited via the SSH username variable. A remote attacker can exploit this to bypass authentication and execute arbitrary commands which could cause memory corruption
last seen2020-06-01
modified2020-06-02
plugin id122855
published2019-03-14
reporterThis script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/122855
titleFortinet FortiOS 5.6.0 Remote Code Execution (FG-IR-18-018)
code
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(122855);
  script_version("1.2");
  script_cvs_date("Date: 2019/10/30 13:24:46");

  script_cve_id("CVE-2018-1352");
  script_bugtraq_id(106960);

  script_name(english:"Fortinet FortiOS 5.6.0 Remote Code Execution (FG-IR-18-018)");
  script_summary(english:"Checks the version of FortiOS.");

  script_set_attribute(attribute:"synopsis", value:"The remote host may be affected by unauthorized code execution which
  could possibly lead to memory corruption.");
  script_set_attribute(attribute:"description", value:
"The version of Fortinet FortiOS running on the remote device is 5.6.0.
It is, therefore, affected by a remote execution vulnerability which
can be exploited via the SSH username variable. A remote attacker
can exploit this to bypass authentication and execute arbitrary
commands which could cause memory corruption");
  script_set_attribute(attribute:"see_also", value:"https://fortiguard.com/psirt/FG-IR-18-018");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Fortinet FortiOS version 5.6.1 or later.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/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:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2018-1352");
  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/02/11");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/02/11");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/03/14");

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:fortinet:fortios");
  script_end_attributes();

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

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

  script_dependencies("fortinet_version.nbin");
  script_require_keys("Host/Fortigate/model", "Host/Fortigate/version", "Settings/ParanoidReport");

  exit(0);
}

include("audit.inc");
include("vcf.inc");

app_name = "FortiOS";

# there is a workaround
if (report_paranoia < 2) audit(AUDIT_PARANOID);

app_info = vcf::get_app_info(app:app_name, kb_ver:"Host/Fortigate/version");

constraints = [
  { "min_version" : "5.6.0", "fixed_version" : "5.6.1" }
];

vcf::check_version_and_report(app_info:app_info, constraints:constraints, severity:SECURITY_HOLE);

References