Vulnerabilities > CVE-2011-2592 - Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability in Citrix Access Gateway Plug-In

047910
CVSS 0.0 - NONE
Attack vector
UNKNOWN
Attack complexity
UNKNOWN
Privileges required
UNKNOWN
Confidentiality impact
UNKNOWN
Integrity impact
UNKNOWN
Availability impact
UNKNOWN
citrix
CWE-119
nessus
NVD
Published: 2014-06-18
Updated: 2017-08-29

Summary

Heap-based buffer overflow in the StartEpa method in the nsepacom ActiveX control (nsepa.exe) in Citrix Access Gateway Enterprise Edition Plug-in for Windows 9.x before 9.3-57.5 and 10.0 before 10.0-69.4 allows remote attackers to execute arbitrary code via a long CSEC HTTP response header.

Vulnerable Configurations

Part Description Count
Application
Citrix
5

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 familyWindows
NASL idCITRIX_ACCESS_GATEWAY_ACTIVEX_NSEPA_STARTEPA.NASL
descriptionThe Citrix Access Gateway ActiveX control for Citrix Access Gateway Enterprise Edition is installed on the remote Windows host. It is the ActiveX component of the Citrix Access Gateway Plug-in for Windows and provides an SSL-based VPN via a web browser. The installed version of this control (nsepa.exe) is affected by the following vulnerabilities involving the
last seen2020-06-01
modified2020-06-02
plugin id62777
published2012-10-31
reporterThis script is Copyright (C) 2012-2018 Tenable Network Security, Inc.
sourcehttps://www.tenable.com/plugins/nessus/62777
titleCitrix Access Gateway Plug-in for Windows ActiveX Control StartEPA() Method HTTP Response Header Parsing Overflows (CTX134303)
code
#
# (C) Tenable Network Security, Inc.
#


include("compat.inc");


if (description)
{
  script_id(62777);
  script_version("1.6");
  script_cvs_date("Date: 2018/11/15 20:50:26");

  script_cve_id("CVE-2011-2592", "CVE-2011-2593");
  script_bugtraq_id(54754);
  script_xref(name:"Secunia", value:"45299");
  script_xref(name:"IAVB", value:"2012-B-0077");

  script_name(english:"Citrix Access Gateway Plug-in for Windows ActiveX Control StartEPA() Method HTTP Response Header Parsing Overflows (CTX134303)");
  script_summary(english:"Checks control's version / kill bit");

  script_set_attribute(
    attribute:"synopsis",
    value:
"The remote Windows host has an ActiveX control that is affected by
multiple buffer overflow vulnerabilities."
  );
  script_set_attribute(
    attribute:"description",
    value:
"The Citrix Access Gateway ActiveX control for Citrix Access Gateway
Enterprise Edition is installed on the remote Windows host.  It is the
ActiveX component of the Citrix Access Gateway Plug-in for Windows and
provides an SSL-based VPN via a web browser.

The installed version of this control (nsepa.exe) is affected by the
following vulnerabilities involving the 'StartEPA()' method that could
lead to arbitrary code execution :

  - A boundary error exists that can be exploited to cause
    a heap-based buffer overflow when processing overly
    long 'CSEC' HTTP response headers. (CVE-2011-2592)

  - An integer overflow exists that can be exploited to
    cause a heap-based buffer overflow when processing
    specially crafted 'Content-Length' HTTP response
    headers. (CVE-2011-2593)"
  );
  script_set_attribute(attribute:"see_also", value:"https://www.securityfocus.com/archive/1/523728/30/0/threaded");
  script_set_attribute(attribute:"see_also", value:"https://www.securityfocus.com/archive/1/523729/30/0/threaded");
  script_set_attribute(attribute:"see_also", value:"https://support.citrix.com/article/CTX134303");
  script_set_attribute(
    attribute:"solution",
    value:
"Update to version 9.3-57.5 / 10.0-69.4 or set the kill bit for the
control."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/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:"vuln_publication_date", value:"2012/08/01");
  script_set_attribute(attribute:"patch_publication_date", value:"2012/08/02");
  script_set_attribute(attribute:"plugin_publication_date", value:"2012/10/31");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:citrix:access_gateway");
  script_set_attribute(attribute:"stig_severity", value:"II");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2012-2018 Tenable Network Security, Inc.");

  script_dependencies("smb_hotfixes.nasl");
  script_require_keys("SMB/Registry/Enumerated");
  script_require_ports(139, 445);

  exit(0);
}


include("audit.inc");
include("global_settings.inc");
include("misc_func.inc");
include("smb_func.inc");
include("smb_activex_func.inc");


get_kb_item_or_exit("SMB/Registry/Enumerated");
if (activex_init() != ACX_OK) audit(code:1, AUDIT_FN_FAIL, 'activex_init');


# Test each control
info = "";
clsids = make_list(
  # 9.x
  '{391DFC1F-B9B9-4A3D-A352-9A541A3630A6}',
  # 10.x
  '{69B69991-62EC-4b51-9E72-8FC664BEC7DB}'
);

not_vuln_ver_installed = FALSE;

foreach clsid (clsids)
{
  file = activex_get_filename(clsid:clsid);
  if (isnull(file))
  {
    activex_end();
    audit(AUDIT_FN_FAIL, 'activex_get_filename', 'NULL');
  }
  if (!file) continue;

  # Get its version.
  version = activex_get_fileversion(clsid:clsid);
  if (!version)
  {
    activex_end();
    audit(AUDIT_VER_FAIL, file);
  }
  ver_pat = "^([0-9]+\.[0-9]+)\.([0-9]+\.[0-9]+)$";
  version_ui = ereg_replace(pattern:ver_pat, replace:"\1-\2", string:version);

  ver = split(version,sep:'.', keep:FALSE);
  for (x=0; x<max_index(ver); x++)
    ver[x] = int(ver[x]);

  # And check it.
  # Affected versions :
  #   10.x < 10.0-69.4
  #   9.x < 9.3-57.5
  if (
    (
      clsid == '{69B69991-62EC-4b51-9E72-8FC664BEC7DB}' &&
      ver[0] == 10 && ver[1] == 0 &&
      (
        ver[2] < 69 ||
        (
          ver[2] == 69 && ver[3] < 4
        )
      )
    ) ||
    (
      clsid == '{391DFC1F-B9B9-4A3D-A352-9A541A3630A6}' &&
      ver[0] == 9 &&
      (
        ver[1] < 5 ||
        (
          ver[1] == 5 &&
          (
            ver[2] < 57 ||
            (
              ver[2] == 57 && ver[3] < 5
            )
          )
        )
      )
    )
  )
  {
    vuln_version = TRUE;
    if (report_paranoia > 1 || activex_get_killbit(clsid:clsid) == 0)
    {
      info = '\n  Class identifier  : ' + clsid +
             '\n  Filename          : ' + file +
             '\n  Installed version : ' + version_ui +
             '\n  Fixed version     : 9.3-57.5 / 10.0-69.4\n';
    }
  }
  else
  {
    not_vuln_ver_installed = TRUE;
    not_vuln_version = version_ui;
    not_vuln_path = file;
  }
}
activex_end();

# Report findings.
if (info)
{
  if (report_paranoia > 1)
  {
    report = info +
      '\n' +
      'Note, though, that Nessus did not check whether the kill bit was\n' +
      "set for the control's CLSID because of the Report Paranoia setting" + '\n' +
      'in effect when this scan was run.\n';
  }
  else
  {
    report = info +
      '\n' +
      'Moreover, its kill bit is not set so it is accessible via Internet\n' +
      'Explorer.\n';
  }

  if (report_verbosity > 0) security_hole(port:kb_smb_transport(), extra:report);
  else security_hole(kb_smb_transport());

  exit(0);
}
else
{
  if (vuln_version == TRUE) audit(AUDIT_ACTIVEX, version_ui);
  else
  {
    if (not_vuln_ver_installed) audit(AUDIT_INST_PATH_NOT_VULN, "'nsepa.exe'", not_vuln_version, not_vuln_path);
    else audit(AUDIT_NOT_INST, "'nsepacom' control");
  }
}

References