Vulnerabilities > CVE-2017-7945 - Information Exposure Through an Error Message vulnerability in Paloaltonetworks Pan-Os

047910
CVSS 5.0 - MEDIUM
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
PARTIAL
Integrity impact
NONE
Availability impact
NONE
network
low complexity
paloaltonetworks
CWE-209
nessus

Summary

The GlobalProtect external interface in Palo Alto Networks PAN-OS before 6.1.17, 7.x before 7.0.15, 7.1.x before 7.1.9, and 8.x before 8.0.2 provides different error messages for failed login attempts depending on whether the username exists, which allows remote attackers to enumerate account names and conduct brute-force attacks via a series of requests, aka PAN-SA-2017-0014 and PAN-72769.

Vulnerable Configurations

Part Description Count
OS
Paloaltonetworks
138

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Fuzzing for garnering J2EE/.NET-based stack traces, for application mapping
    An attacker sends random, malformed, or otherwise unexpected messages to a target application and observes any stack traces produced by error messages. Fuzzing techniques involve sending random or malformed messages to a target and monitoring the target's response. The attacker does not initially know how a target will respond to individual messages but by attempting a large number of message variants they may find a variant that trigger's desired behavior. In this attack, the purpose of the fuzzing is to cause the targeted application to return an error including a stack trace, although fuzzing a target can also sometimes cause the target to enter an unstable state, causing a crash. The stack trace enumerates the chain of methods that led up to the point where the error was encountered. This can not only reveal the names of the methods (some of which may have known weaknesses) but possibly also the location of class files and libraries as well as parameter values. In some cases, the stack trace might even disclose sensitive configuration or user information.
  • Fuzzing and observing application log data/errors for application mapping
    An attacker sends random, malformed, or otherwise unexpected messages to a target application and observes the application's log or error messages returned. Fuzzing techniques involve sending random or malformed messages to a target and monitoring the target's response. The attacker does not initially know how a target will respond to individual messages but by attempting a large number of message variants they may find a variant that trigger's desired behavior. In this attack, the purpose of the fuzzing is to observe the application's log and error messages, although fuzzing a target can also sometimes cause the target to enter an unstable state, causing a crash. By observing logs and error messages, the attacker can learn details about the configuration of the target application and might be able to cause the target to disclose sensitive information.
  • Padding Oracle Crypto Attack
    An attacker is able to efficiently decrypt data without knowing the decryption key if a target system leaks data on whether or not a padding error happened while decrypting the ciphertext. A target system that leaks this type of information becomes the padding oracle and an attacker is able to make use of that oracle to efficiently decrypt data without knowing the decryption key by issuing on average 128*b calls to the padding oracle (where b is the number of bytes in the ciphertext block). In addition to performing decryption, an attacker is also able to produce valid ciphertexts (i.e., perform encryption) by using the padding oracle, all without knowing the encryption key. Any cryptosystem can be vulnerable to padding oracle attacks if the encrypted messages are not authenticated to ensure their validity prior to decryption, and then the information about padding error is leaked to the attacker. This attack technique may be used, for instance, to break CAPTCHA systems or decrypt/modify state information stored in client side objects (e.g., hidden fields or cookies). This attack technique is a side-channel attack on the cryptosystem that uses a data leak from an improperly implemented decryption routine to completely subvert the cryptosystem. The one bit of information that tells the attacker whether a padding error during decryption has occurred, in whatever form it comes, is sufficient for the attacker to break the cryptosystem. That bit of information can come in a form of an explicit error message about a padding error, a returned blank page, or even the server taking longer to respond (a timing attack). This attack can be launched cross domain where an attacker is able to use cross-domain information leaks to get the bits of information from the padding oracle from a target system / service with which the victim is communicating. To do so an attacker sends a request containing ciphertext to the target system. Due to the browser's same origin policy, the attacker is not able to see the response directly, but can use cross-domain information leak techniques to still get the information needed (i.e., information on whether or not a padding error has occurred). For instance, this can be done using "img" tag plus the onerror()/onload() events. The attacker's JavaScript can make web browsers to load an image on the target site, and know if the image is loaded or not. This is 1-bit information needed for the padding oracle attack to work: if the image is loaded, then it is valid padding, otherwise it is not.
  • Probe Application Error Reporting
    An Attacker, aware of an application's location (and possibly authorized to use the application) can probe the application's structure and evaluate its robustness by probing its error conditions (not unlike one would during a 'fuzz' test, but more purposefully here) in order to support attacks such as blind SQL injection, or for the more general task of mapping the application to mount another subsequent attack.
  • Blind SQL Injection
    Blind SQL Injection results from an insufficient mitigation for SQL Injection. Although suppressing database error messages are considered best practice, the suppression alone is not sufficient to prevent SQL Injection. Blind SQL Injection is a form of SQL Injection that overcomes the lack of error messages. Without the error messages that facilitate SQL Injection, the attacker constructs input strings that probe the target through simple Boolean SQL expressions. The attacker can determine if the syntax and structure of the injection was successful based on whether the query was executed or not. Applied iteratively, the attacker determines how and where the target is vulnerable to SQL Injection. For example, an attacker may try entering something like "username' AND 1=1; --" in an input field. If the result is the same as when the attacker entered "username" in the field, then the attacker knows that the application is vulnerable to SQL Injection. The attacker can then ask yes/no questions from the database server to extract information from it. For example, the attacker can extract table names from a database using the following types of queries: If the above query executes properly, then the attacker knows that the first character in a table name in the database is a letter between m and z. If it doesn't, then the attacker knows that the character must be between a and l (assuming of course that table names only contain alphabetic characters). By performing a binary search on all character positions, the attacker can determine all table names in the database. Subsequently, the attacker may execute an actual attack and send something like:

Nessus

NASL familyPalo Alto Local Security Checks
NASL idPALO_ALTO_PAN-OS_7_0_15.NASL
descriptionThe version of Palo Alto Networks PAN-OS running on the remote host is 6.1.x prior to 6.1.17, 7.0.x prior to 7.0.15, 7.1.x prior to 7.1.10, or 8.0.x prior to 8.0.2. It is, therefore, affected by multiple vulnerabilities : - A flaw exists in the GNU wget component when handling server redirects to FTP resources due to the destination file name being obtained from the redirected URL and not the original URL. An unauthenticated, remote attacker can exploit this, via a specially crafted response, to cause a different file name to be used than intended, resulting in writing to arbitrary files. (CVE-2016-4971) - A flaw exists in the Linux kernel due to improper determination of the rate of challenge ACK segments. An unauthenticated, remote attacker can exploit this to gain access to the shared counter, which makes it easier to hijack TCP sessions using a blind in-window attack. This issue only affects version 7.1.x. (CVE-2016-5696) - An out-of-bounds read error exists when handling packets using the CHACHA20/POLY1305 or RC4-MD5 ciphers. An unauthenticated, remote attacker can exploit this, via specially crafted truncated packets, to cause a denial of service condition. This issue does not affect version 6.1.x. (CVE-2017-3731) - A cross-site scripting (XSS) vulnerability exists in GlobalProtect due to improper validation of user-supplied input to unspecified request parameters before returning it to users. An unauthenticated, remote attacker can exploit this, via a specially crafted request, to execute arbitrary script code in a user
last seen2020-06-01
modified2020-06-02
plugin id100419
published2017-05-25
reporterThis script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/100419
titlePalo Alto Networks PAN-OS 6.1.x < 6.1.17 / 7.0.x < 7.0.15 / 7.1.x < 7.1.10 / 8.0.x < 8.0.2 Multiple Vulnerabilities
code
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(100419);
  script_version("1.11");
  script_cvs_date("Date: 2019/01/02 11:18:37");

  script_cve_id(
    "CVE-2016-4971",
    "CVE-2016-5696",
    "CVE-2017-3731",
    "CVE-2017-7409",
    "CVE-2017-7644",
    "CVE-2017-7945"
  );
  script_bugtraq_id(
    91530,
    91704,
    95813,
    98404,
    97953,
    98396
  );
  script_xref(name:"EDB-ID", value:"40064");

  script_name(english:"Palo Alto Networks PAN-OS 6.1.x < 6.1.17 / 7.0.x < 7.0.15 / 7.1.x < 7.1.10 / 8.0.x < 8.0.2 Multiple Vulnerabilities");
  script_summary(english:"Checks the PAN-OS version.");

  script_set_attribute(attribute:"synopsis", value:
"The remote host is affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description",value:
"The version of Palo Alto Networks PAN-OS running on the remote host is
6.1.x prior to 6.1.17, 7.0.x prior to 7.0.15, 7.1.x prior to 7.1.10,
or 8.0.x prior to 8.0.2. It is, therefore, affected by multiple
vulnerabilities :

  - A flaw exists in the GNU wget component when handling
    server redirects to FTP resources due to the destination
    file name being obtained from the redirected URL and not
    the original URL. An unauthenticated, remote attacker
    can exploit this, via a specially crafted response, to
    cause a different file name to be used than intended,
    resulting in writing to arbitrary files. (CVE-2016-4971)

  - A flaw exists in the Linux kernel due to improper
    determination of the rate of challenge ACK segments. An
    unauthenticated, remote attacker can exploit this to
    gain access to the shared counter, which makes it easier
    to hijack TCP sessions using a blind in-window attack.
    This issue only affects version 7.1.x. (CVE-2016-5696)

  - An out-of-bounds read error exists when handling packets
    using the CHACHA20/POLY1305 or RC4-MD5 ciphers. An
    unauthenticated, remote attacker can exploit this, via
    specially crafted truncated packets, to cause a denial
    of service condition. This issue does not affect version
    6.1.x. (CVE-2017-3731)

  - A cross-site scripting (XSS) vulnerability exists in
    GlobalProtect due to improper validation of
    user-supplied input to unspecified request parameters
    before returning it to users. An unauthenticated, remote
    attacker can exploit this, via a specially crafted
    request, to execute arbitrary script code in a user's
    browser session. This issue only affects version 7.0.x.
    (CVE-2017-7409)

  - A flaw exists in the web-based management interface due
    to improper permission checks that allows an
    authenticated, remote attacker to disclose sensitive
    information. This issue only affects versions 6.1.x,
    7.0.x, and 8.0.x. (CVE-2017-7644)

  - An information disclosure vulnerability exists in the
    GlobalProtect external interface due to returning
    different error messages when handling login attempts
    with valid or invalid usernames. An unauthenticated,
    remote attacker can exploit this to enumerate valid
    user accounts. This issue only affects versions 6.1.x,
    7.0.x, and 8.0.x. (CVE-2017-7945)

  - A denial of service vulnerability exists in the firewall
    when handling stale responses to authentication requests
    prior to selecting CHAP or PAP as the protocol. An
    unauthenticated, remote attacker can exploit this to
    cause the authentication process (authd) to stop
    responding. This issue only affects versions 7.0.x and
    7.1.x.

  - An information disclosure vulnerability exists when
    viewing changes in the configuration log due to the
    'Auth Password' and 'Priv Password' for the SNMPv3
    server profile not being properly masked. A local
    attacker can exploit this to disclose password
    information. This issue only affects versions 7.1.x and
    8.0.x.

  - A denial of service vulnerability exists due to a flaw
    when handling HA3 messages. An unauthenticated, remote
    attacker can exploit this to cause several processes to
    stop. This issue only affects version 7.1.x.
");
  # https://www.paloaltonetworks.com/documentation/80/pan-os/pan-os-release-notes/pan-os-8-0-2-addressed-issues
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?0d96265b");
  # https://www.paloaltonetworks.com/documentation/80/pan-os/pan-os-release-notes/pan-os-8-0-1-addressed-issues
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?1f083775");
  # https://www.paloaltonetworks.com/documentation/80/pan-os/pan-os-release-notes/pan-os-8-0-0-addressed-issues
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?aacbe40b");
  # https://www.paloaltonetworks.com/documentation/71/pan-os/pan-os-release-notes/pan-os-7-1-10-addressed-issues
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?49c666f2");
  # https://www.paloaltonetworks.com/documentation/70/pan-os/pan-os-release-notes/pan-os-7-0-15-addressed-issues
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?fe505ba3");
  # https://www.paloaltonetworks.com/documentation/61/pan-os/pan-os-release-notes/pan-os-6-1-17-addressed-issues
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?9254ef1a");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Palo Alto Networks PAN-OS version 6.1.17 / 7.0.15 /
7.1.10 / 8.0.2 or later.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2016/06/09");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/04/20");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/05/25");

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

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

  script_copyright(english:"This script is Copyright (C) 2017-2019 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");

  exit(0);
}

include("vcf.inc");

app_name = "Palo Alto Networks PAN-OS";

app_info = vcf::get_app_info(app:app_name, kb_ver:"Host/Palo_Alto/Firewall/Full_Version", webapp:true);

vcf::check_granularity(app_info:app_info, sig_segments:3);

constraints = [
  {"min_version" : "8.0.0", "max_version" : "8.0.1",  "fixed_version" : "8.0.2"  },
  {"min_version" : "7.1.0", "max_version" : "7.1.9",  "fixed_version" : "7.1.10" },
  {"min_version" : "7.0.0", "max_version" : "7.0.14", "fixed_version" : "7.0.15" },
  {"min_version" : "6.1.0", "max_version" : "6.1.16", "fixed_version" : "6.1.17" }
];

vcf::check_version_and_report(app_info:app_info, constraints:constraints, severity:SECURITY_WARNING, flags:{xss:true});