Vulnerabilities > CVE-2020-1992 - Use of Externally-Controlled Format String vulnerability in Paloaltonetworks Pan-Os

047910
CVSS 9.3 - CRITICAL
Attack vector
NETWORK
Attack complexity
MEDIUM
Privileges required
NONE
Confidentiality impact
COMPLETE
Integrity impact
COMPLETE
Availability impact
COMPLETE
network
paloaltonetworks
CWE-134
critical
nessus
NVD
Published: 2020-04-08
Updated: 2020-04-10

Summary

A format string vulnerability in the Varrcvr daemon of PAN-OS on PA-7000 Series devices with a Log Forwarding Card (LFC) allows remote attackers to crash the daemon creating a denial of service condition or potentially execute code with root privileges. This issue affects Palo Alto Networks PAN-OS 9.0 versions before 9.0.7; PAN-OS 9.1 versions before 9.1.2 on PA-7000 Series devices with an LFC installed and configured. This issue requires WildFire services to be configured and enabled. This issue does not affect PAN-OS 8.1 and earlier releases. This issue does not affect any other PA Series firewalls.

Vulnerable Configurations

Part Description Count
OS
Paloaltonetworks
10
Hardware
Paloaltonetworks
2

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 familyPalo Alto Local Security Checks
NASL idPALO_ALTO_PAN-SA-2020-1992.NASL
descriptionThe version of Palo Alto Networks PAN-OS running on the remote host is 9.0.x prior to 9.0.7 or 9.1.x prior to 9.1.2. It is, therefore, affected by a remote code execution vulnerability. Improper restriction of communications to Log Forwarding Card (LFC) on PA-7000 Series devices with the WildFire service enabled may allow an unauthenticated attacker with network access to the LFC to gain root access to PAN-OS. Note that Nessus has not tested for this issue but has instead relied only on the application
last seen2020-06-12
modified2020-06-11
plugin id137355
published2020-06-11
reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/137355
titlePalo Alto Networks PAN-OS Series PA-7000 9.0 < 9.0.7 / 9.1 < 9.1.2 RCE
code
#
# (C) Tenable Network Security, Inc.
#

include('compat.inc');

if (description)
{
  script_id(137355);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/07/03");

  script_cve_id("CVE-2020-1992");
  script_xref(name:"IAVA", value:"2020-A-0222-S");

  script_name(english:"Palo Alto Networks PAN-OS Series PA-7000 9.0 < 9.0.7 / 9.1 < 9.1.2 RCE");

  script_set_attribute(attribute:"synopsis", value:
"The remote host is affected by a remote code execution vulnerability.");
  script_set_attribute(attribute:"description", value:
"The version of Palo Alto Networks PAN-OS running on the remote host is 9.0.x prior to 9.0.7 or 9.1.x prior to 9.1.2.
It is, therefore, affected by a remote code execution vulnerability. Improper restriction of communications to Log
Forwarding Card (LFC) on PA-7000 Series devices with the WildFire service enabled may allow an unauthenticated attacker
with network access to the LFC to gain root access to PAN-OS.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://security.paloaltonetworks.com/CVE-2020-1992");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Palo Alto Networks PAN-OS 9.0.7, 9.1.2 or later");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:C/I:C/A: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_attribute(attribute:"cvss_score_source", value:"CVE-2020-1992");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/04/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/04/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/06/11");

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:paloaltonetworks:pan-os");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Palo Alto Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("palo_alto_version.nbin");
  script_require_keys("Host/Palo_Alto/Firewall/Version", "Host/Palo_Alto/Firewall/Full_Version", "Settings/ParanoidReport");

  exit(0);
}

include('vcf.inc');
include('vcf_extras.inc');

app_name = 'Palo Alto Networks PAN-OS';
vcf::palo_alto::initialize();

app_info = vcf::get_app_info(app:app_name, kb_ver:'Host/Palo_Alto/Firewall/Full_Version', kb_source:'Host/Palo_Alto/Firewall/Source');
model = get_kb_item_or_exit('Host/Palo_Alto/Firewall/Model');

if (  model !~ 'PA-7[0-9][0-9][0-9]($|[^0-9])') {
  audit(AUDIT_HOST_NOT, 'an affected model');
}

# We cannot test if LFS is installed and configured
if (report_paranoia < 2) audit(AUDIT_PARANOID);

constraints = [
  { 'min_version' : '9.0.0', 'fixed_version' : '9.0.7' },
  { 'min_version' : '9.1.0', 'fixed_version' : '9.1.2' }
];

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

References