Asterisk main/udptl.c Buffer Overflows (AST-2011-002)

#%NASL_MIN_LEVEL 70300
#
# (C) Tenable Network Security, Inc.
#

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(52157);
  script_version("1.19");
  script_set_attribute(attribute:"plugin_modification_date", value:"2022/04/11");

  script_cve_id("CVE-2011-1147");
  script_bugtraq_id(46474);
  script_xref(name:"SECUNIA", value:"43429");

  script_name(english:"Asterisk main/udptl.c Buffer Overflows (AST-2011-002)");

  script_set_attribute(attribute:"synopsis", value:
"A telephony application running on the remote host is affected by
multiple buffer overflow vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"According to the version in its SIP banner, the version of Asterisk
running on the remote host may be vulnerable to heap- and stack-buffer
overflow attacks with specially crafted UDPTL packets.

Successful exploitation requires T.38 support to be enabled on the
target, which is not the default, and can allow execution of arbitrary
code in the context of the Asterisk server or an application crash.

Note that Nessus has not determined whether T.38 is actually enabled
so this finding may be a false positive.");
  script_set_attribute(attribute:"see_also", value:"http://downloads.asterisk.org/pub/security/AST-2011-002.html");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Asterisk 1.4.39.2 / 1.6.1.22 / 1.6.2.16.2 / 1.8.2.4 or
Asterisk Business Edition C.3.6.3 or later.

Alternatively, disable T.38 support by setting 't38pt_udptl' to 'no'
in 'sip.conf' and ensuring that the chan_ooh323 module is not
loaded.");
  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_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:"2011/01/27");
  script_set_attribute(attribute:"patch_publication_date", value:"2011/02/21");
  script_set_attribute(attribute:"plugin_publication_date", value:"2011/02/23");

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:digium:asterisk");
  script_set_attribute(attribute:"thorough_tests", value:"true");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Gain a shell remotely");

  script_copyright(english:"This script is Copyright (C) 2011-2022 Tenable Network Security, Inc.");

  script_dependencies("asterisk_detection.nasl");
  script_require_keys("asterisk/sip_detected", "Settings/ParanoidReport");

  exit(0);
}

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

get_kb_item_or_exit("asterisk/sip_detected");

# see if we were able to get version info from the Asterisk SIP services
asterisk_kbs = get_kb_list("sip/asterisk/*/version");
if (isnull(asterisk_kbs)) exit(1, "Could not obtain any version information from the Asterisk SIP instance(s).");

# Prevent potential false positives.
if (report_paranoia < 2) audit(AUDIT_PARANOID);

is_vuln = FALSE;
not_vuln_installs = make_list();
errors = make_list();

foreach kb_name (keys(asterisk_kbs))
{
  vulnerable = 0;

  matches = eregmatch(pattern:"/(udp|tcp)/([0-9]+)/version", string:kb_name);
  if (isnull(matches))
  {
    errors = make_list(errors, "Unexpected error parsing port number from kb name: "+kb_name);
    continue;
  }

  proto = matches[1];
  port  = matches[2];
  version = asterisk_kbs[kb_name];

  if (version == 'unknown')
  {
    errors = make_list(errors, "Unable to obtain version of install on " + proto + "/" + port);
    continue;
  }

  banner = get_kb_item("sip/asterisk/" + proto + "/" + port + "/source");
  if (!banner)
  {
    # We have version but banner is missing; log error
    # and use in version-check though.
    errors = make_list(errors, "KB item 'sip/asterisk/" + proto + "/" + port + "/source' is missing");
    banner = 'unknown';
  }

  if (version =~ '^1\\.4([^0-9]|$)')
  {
    fixed = "1.4.39.2";
    vulnerable = ver_compare(ver:version, fix:fixed, app:"asterisk");
  }
  else if (version =~ '^1\\.6([^0-9]|$)')
  {
    if (version =~ '^1\\.6\\.1([^0-9]|$)')
    {
      fixed = "1.6.1.22";
      vulnerable = ver_compare(ver:version, fix:fixed, app:"asterisk");
    }
    else if (version =~ '^1\\.6\\.2([^0-9]|$)')
    {
      fixed = "1.6.2.16.2";
      if (version =~ '^1\\.6\\.2\\.16([^0-9]|$)')
        vulnerable = ver_compare(ver:version, fix:fixed, app:"asterisk");
      else
        vulnerable = ver_compare(ver:version, fix:"1.6.2.17", app:"asterisk");
    }
    else
    {
      # Recommend lowest patched version in the 1.6 branch.
      fixed = "1.6.1.22";
      vulnerable = ver_compare(ver:version, fix:"1.6.3", app:"asterisk");
    }
  }
  else if (version =~ '^1\\.8([^0-9]|$)')
  {
    fixed = "1.8.2.4";
    vulnerable = ver_compare(ver:version, fix:fixed, app:"asterisk");
  }
  else if (version =~ '^[A-Z]')
  {
    fixed = "C.3.6.3";

    if (version[0] <= "B")
    {
      vulnerable = -1;
    }
    else if (version[0] > "C")
    {
      vulnerable = 1;
    }
    else
    {
      tmp_fixed = substr(fixed, 2);
      tmp_version = substr(version, 2);
      vulnerable = ver_compare(ver:tmp_version, fix:tmp_fixed, app:"asterisk");
    }
  }

  if (vulnerable < 0)
  {
    is_vuln = TRUE;
    if (report_verbosity > 0)
    {
      report =
        '\n  Version source    : ' + banner +
        '\n  Installed version : ' + version +
        '\n  Fixed version     : ' + fixed + '\n';
      security_hole(port:port, proto:proto, extra:report);
    }
    else security_hole(port:port, proto:proto);
  }
  else not_vuln_installs = make_list(not_vuln_installs, version + " on port " + proto + "/" + port);
}

if (max_index(errors))
{
  if (max_index(errors) == 1) errmsg = errors[0];
  else errmsg = 'Errors were encountered verifying installs : \n  ' + join(errors, sep:'\n  ');

  exit(1, errmsg);
}
else
{
  installs = max_index(not_vuln_installs);
  if (installs == 0)
  {
    if (is_vuln)
      exit(0);
    else
      audit(AUDIT_NOT_INST, "Asterisk");
  }
  else if (installs == 1) audit(AUDIT_INST_VER_NOT_VULN, "Asterisk " + not_vuln_installs[0]);
  else exit(0, "The Asterisk installs (" + join(not_vuln_installs, sep:", ") + ") are not affected.");
}