Vulnerabilities > CVE-2019-19781 - Path Traversal vulnerability in Citrix products

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
citrix
CWE-22
critical
nessus
exploit available
metasploit
NVD
Published: 2019-12-27
Updated: 2023-01-20

Summary

An issue was discovered in Citrix Application Delivery Controller (ADC) and Gateway 10.5, 11.1, 12.0, 12.1, and 13.0. They allow Directory Traversal.

Vulnerable Configurations

Part Description Count
OS
Citrix
10
Hardware
Citrix
3

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Relative Path Traversal
    An attacker exploits a weakness in input validation on the target by supplying a specially constructed path utilizing dot and slash characters for the purpose of obtaining access to arbitrary files or resources. An attacker modifies a known path on the target in order to reach material that is not available through intended channels. These attacks normally involve adding additional path separators (/ or \) and/or dots (.), or encodings thereof, in various combinations in order to reach parent directories or entirely separate trees of the target's directory structure.
  • Directory Traversal
    An attacker with access to file system resources, either directly or via application logic, will use various file path specification or navigation mechanisms such as ".." in path strings and absolute paths to extend their range of access to inappropriate areas of the file system. The attacker attempts to either explore the file system for recon purposes or access directories and files that are intended to be restricted from their access. Exploring the file system can be achieved through constructing paths presented to directory listing programs, such as "ls" and 'dir', or through specially crafted programs that attempt to explore the file system. The attacker engaging in this type of activity is searching for information that can be used later in a more exploitive attack. Access to restricted directories or files can be achieved through modification of path references utilized by system applications.
  • File System Function Injection, Content Based
    An attack of this type exploits the host's trust in executing remote content including binary files. The files are poisoned with a malicious payload (targeting the file systems accessible by the target software) by the attacker and may be passed through standard channels such as via email, and standard web content like PDF and multimedia files. The attacker exploits known vulnerabilities or handling routines in the target processes. Vulnerabilities of this type have been found in a wide variety of commercial applications from Microsoft Office to Adobe Acrobat and Apple Safari web browser. When the attacker knows the standard handling routines and can identify vulnerabilities and entry points they can be exploited by otherwise seemingly normal content. Once the attack is executed, the attackers' program can access relative directories such as C:\Program Files or other standard system directories to launch further attacks. In a worst case scenario, these programs are combined with other propagation logic and work as a virus.
  • Using Slashes and URL Encoding Combined to Bypass Validation Logic
    This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple way of encoding an URL and abuse the interpretation of the URL. An URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
  • Manipulating Input to File System Calls
    An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.

Exploit-Db

  • idEDB-ID:47930
    last seen2020-01-16
    modified2020-01-16
    published2020-01-16
    reporterExploit-DB
    sourcehttps://www.exploit-db.com/download/47930
    titleCitrix Application Delivery Controller (ADC) and Gateway 13.0 - Path Traversal
  • idEDB-ID:47901
    last seen2020-01-11
    modified2020-01-11
    published2020-01-11
    reporterExploit-DB
    sourcehttps://www.exploit-db.com/download/47901
    titleCitrix Application Delivery Controller and Citrix Gateway - Remote Code Execution (PoC)

Metasploit

Nessus

  • NASL familyCGI abuses
    NASL idCITRIX_NETSCALER_CTX267027.NASL
    descriptionThe remote Citrix ADC or Citrix NetScaler Gateway device is affected by an arbitrary code execution vulnerability. An unauthenticated, remote attacker may be able to leverage this vulnerability to perform arbitrary code execution on an affected host. Please refer to advisory CTX267027 for more information.
    last seen2020-06-01
    modified2020-06-02
    plugin id132397
    published2019-12-24
    reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/132397
    titleCitrix ADC and Citrix NetScaler Gateway Arbitrary Code Execution (CTX267027)
    code
    #
# (C) Tenable Network Security, Inc.
#
include('compat.inc');

if (description)
{
  script_id(132397);
  script_version("1.10");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/07/10");

  script_cve_id("CVE-2019-19781");
  script_xref(name:"IAVA", value:"2020-A-0001-S");

  script_name(english:"Citrix ADC and Citrix NetScaler Gateway Arbitrary Code Execution (CTX267027)");

  script_set_attribute(attribute:"synopsis", value:"
  The remote device is affected by an arbitrary code execution vulnerability.");
  script_set_attribute(attribute:"description", value:
"The remote Citrix ADC or Citrix NetScaler Gateway device is affected by an arbitrary code execution vulnerability.
An unauthenticated, remote attacker may be able to leverage this vulnerability to perform arbitrary code execution on 
an affected host.

Please refer to advisory CTX267027 for more information.");
  script_set_attribute(attribute:"see_also", value:"https://support.citrix.com/article/CTX267027");
  script_set_attribute(attribute:"solution", value:
"For versions 10.5.x, 11.1.x, 12.0.x, 12.1.x and 13.0.x, upgrade to 10.5.70.12, 11.1.63.15, 12.0.63.13, 12.1.55.18 and 
13.0.47.24 respectively.");
  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:F/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:F/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2019-19781");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"metasploit_name", value:'Citrix ADC (NetScaler) Directory Traversal RCE');
  script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/12/17");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/12/17");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/12/24");

  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:citrix:netscaler_access_gateway_firmware");
  script_set_attribute(attribute:"stig_severity", value:"II");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"CGI abuses");

  script_copyright(english:"This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("citrix_netscaler_detect.nbin");
  script_require_keys("Host/NetScaler/Detected");

  exit(0);
}

include('audit.inc');

version = get_kb_item_or_exit('Host/NetScaler/Version');
build = get_kb_item('Host/NetScaler/Build');

display_version = version + '-' + build;
version = version + '.' + build;

fixed_build = NULL;

if (version =~ '^10\\.5' && ver_compare(ver:build, fix:'70.12', strict:FALSE) == -1)
  fixed_build = '10.5-70.12';

if (version =~ '^11\\.1' && ver_compare(ver:build, fix:'63.15', strict:FALSE) == -1)
  fixed_build = '11.1-63.15';

if (version =~ '^12\\.0' && ver_compare(ver:build, fix:'63.13', strict:FALSE) == -1)
  fixed_build = '12.0-63.13';

if (version =~ '^12\\.1' && ver_compare(ver:build, fix:'55.18', strict:FALSE) == -1)
  fixed_build = '12.1-55.18';

if (version =~ '^13\\.0' && ver_compare(ver:build, fix:'47.24', strict:FALSE) == -1)
  fixed_build = '13.0-47.24';

if (isnull(fixed_build))
  audit(AUDIT_INST_VER_NOT_VULN, 'Citrix NetScaler', display_version);

report =
   '\n  Installed version : ' + display_version +
   '\n  Installed build   : ' + build +
   '\n  Fixed build       : ' + fixed_build +
   '\n';

security_report_v4(port:0, severity:SECURITY_HOLE, extra:report);
  • NASL familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_2BAB995F36D411EA9DAD002590ACAE31.NASL
    descriptionArt Manion and Will Dormann report : By using an older and less-secure form of open(), it is possible for untrusted template files to cause reads/writes outside of the template directories. This vulnerability is a component of the recent Citrix exploit.
    last seen2020-06-01
    modified2020-06-02
    plugin id132879
    published2020-01-15
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/132879
    titleFreeBSD : Template::Toolkit -- Directory traversal on write (2bab995f-36d4-11ea-9dad-002590acae31)

Packetstorm

Saint

descriptionCitrix ADC and Gateway directory traversal and XML file upload
idmisc_citrixnetscalerver
titlecitrix_adc_dirtrav_xml_upload
typeremote

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References