Certificates for Authenticity, Authentification or both

Certificates for Authenticity,
Authentification or both?
Wolfgang Voelker | Director Product Management
wolfgang.voelker@wibu.com
Ruediger Kuegler | Security Expert
ruediger.kuegler@wibu.com
Certificates
07.08.2015 Certificates for authenticity, authentification or both? 1

What are Certificates?

Sender
Sending a Signed Message
Data
Data
Signature
Calculate
Hash
Calculate
Signature
Private
Key
Data
Signature
Calculate
Hash
Verify
Signature
Public
Key
Recipient
Yes No

The Challenge!
How do I know that the
public key is genuine?

The Solution
Certificates
(Public Key Certificate, X.509)

A Certificate
 Confirms the owner of a public key
 Identity:
 Person
 Company
 IT-system (i.e. server)
 Signed by issuer
 Attributes
Certificate
Issued for:
Common name (CN): Wolfgang Voelker
Company (O): WIBU-SYSTEMS AG
Business unit (OU): WOPS
Serial number: 1be10001000220613…
Public key: 0x15, 0x3c, 0xd0, 0x26, 0xd6, 0x71,
0xfa, 0xae, 0x20, 0xa6, 0x15, 0x58,
0xea, 0x3d, 0xdd, 0x36, 0x89, …
Issued by:
Common name (CN): Root
..
Valid until: 31.12.2015

The next Challenge!
How do I know that the
certificate is genuine?

The next Solution
The certificate is signed
by the issuer.
(Validation through the public key of the issuer)

The… Challenge!
…?

The final Solution
I already know a
root certificate from a
certification authority.
(Root Certificate / Certificate Authority)

Examples of Root Certificates

Certificate Hierarchy
07.08.2015 Zertifikate für Authentizität, Authentifizierung oder beides? 12
Root Certificate
CN: Root
Certificate
CN: Inter 2
Certificate
CN: Wolfgang
Certificate
CN: Daniel
Certificate
CN: Marc
Certificate
CN: Christian
Certificate
CN: Ruediger
Certificate
CN: Stefan
Certificate
CN: Inter 1
Certificate
CN: Inter 3

Self-signed Certificates
 Self-signed
 No Root-Certificate
 Usually not accepted
 Users have to trust the certificate
manually
Certificate
Issued for:
Common name (CN): Ruediger Kuegler
Business unit (OU): Professional Services
Serial number: 1be10001000220613…
Public key: 0x15, 0x3c, 0xd0, 0x26, 0xd6, 0x71,
0xfa, 0xae, 0x20, 0xa6, 0x15, 0x58,
0xea, 0x3d, 0xdd, 0x36, 0x89, …
Issued by:
Common Name (CN): Ruediger Kuegler
..
Valid until: 31.12.2015

Blacklists
 CRL (Certificate Revocation List)
 Includes invalid certificates (certificate revocation)
 Online enquiry possible, Online Certificate Status Protocol (OCSP)

Use Cases

Use Cases
 Server Certificates
 Client Certificates
 E-Mail Certificates / VPN Certificates
 OPC UA Certificates
 Authenticode
 Code integrity of software
 …

Server Certificates

Client
Server Certificate
Server
Private
Key
Server
Root Certificate
CN: Root
https
Certificate
CN: wibu.com
Client verifies the identity
of the server

Server Certificate – Secure Connection

Server Configuration…
SSLEngine on
SSLCertificateKeyFile "c:/cert/my_private_key.pem"
SSLCertificateFile "c:/cert/the_cert_I_got_from_verisign.crt"

… Server Configuration
 SSLEngine on
 Activates SSL, SSL mode must be enabled
 SSLCertificateKeyFile „c:/cert/my_private_key.pem“
 Private Key
 SSLCertificateFile „c:/cert/the_cert_I_got_from_verisign.crt “
 Certificate

Client Certificates

Client
Client Certificate
Server
Private
Key
Server
Root Certificate
CN: Root
https
Certificate
CN: wibu.com
Client verifies the identity
of the server
Client
Private
Key
Certificate
CN: user
Root Certificate
CN: Wibu Root
Server verifies the identity
of the client

Server Configuration for Client Certificates
SSLEngine on
SSLCertificateKeyFile "c:/cert/my_private_key.pem"
SSLCertificateFile "c:/cert/the_cert_I_got_from_verisign.crt"
SSLCACertificateFile "c:/cert/my_own_ca_root_cert.crt"
SSLVerifyClient require
SSLVerifyDepth 10
SSLRequire %{SSL_CLIENT_S_DN_CN} eq "user@domain.de"
SSLOptions +StdEnvVars

… Server Configuration for the Client Certificate
 SSLCACertificateFile „c:/cert/my_own_ca_root_cert.crt“
 Certificate Authority (CA) for Client Certificates
 SSLVerifyClient require
 Client Certificate required
 SSLRequire %{SSL_CLIENT_S_DN_CN} eq user@domain.de
 Example of a validation
 SSLOptions +StdEnvVars
 Transmission of the parameters to PHP / Application

Issuance of a Client Certificate (recommended)
 Client:
 Generate the key pair
 Generate the Certificate Signing Request (CSR)
 Send the CSR to a CA
 CA / Server:
 Generate a certificate
 Send the certificate to a client
 Client:
 Import the certificate

Creation of a Client Certificate (easy)
 CA / Server:
 Generate the key pair
 Generate the certificate
 Export the private key
 Send certificate + private key to a client
 Client:
 Import the certificate
 Import the private key

Certificate / Private Key
Storage

Saving Private Keys
 File on the file system (PEM file with key)
 Certificate Storage
 PKCS#11
 Microsoft CSP (Crypto Service Provider)
 Physical medium
 On a disk
 In a token

PKCS#11 / Microsoft CSP
PKCS#11 Microsoft CSP
CmDongle
Internet
Explorer
OutlookFirefox OpenVPN
My
Application

Example with a Token: CSSI Middleware

Authenticode

Motivation: the Application
 Signed Application

Started Application

Motivation: the Patch

Motivation: the Question
 Is the application still runnig?

Started Application (with invalid signature)

Is the application still runnig?
The scary answer:
YES

Summary
 Microsoft Windows starts any application
 Without signature
 With valid signature
 With invalid signature
 On-board tools are not suitable for copy / integrity protection

Yes, but…
Yes, but…

Software Check
 Signature validation
 Valid / Invalid?
 Who has signed?
 When was the application signed?
 Reaction in case of invalid signature
 Exit (hiding the calls?)
 „Wrong calculation“ !?

Started Application (with Authenticode check via API)

Started Application (Patched)

The Vulnerability
Own Software
WINTRUST.DLL

The Vulnerability
 A well known and documented Windows API verifies the signature !?
 Attacks:
 Patching WINTRUST.DLL
 Hooking function with standard tools
 Overwriting functions in the dll at runtime from the patched application

Overwrite at runtime
...
fake[0] := $31;
fake[1] := $C0;
fake[2] := $C3;
lib := LoadLibrary('WINTRUST.DLL');
p := GetProcAddress(lib, 'WinVerifyTrust');
VirtualProtect(p, 3, PAGE_EXECUTE_READWRITE, old);
move(fake, p^, 3);
VirtualProtect(p, 3, old, old);
...

Started Application (Patched + Code Inject)

Conclusion: Authenticode
 Certificates provide security only if the validation occurs in a trusted
environment
 Authenticode = Protect the user from viruses
 Authenticode ≠ Protection against piracy

Code Signature
with AxProtector

Protection Suite
Wibu-Systems Protection Suite
07.08.2015 Certificates for authenticity, authentification or both?
Automatic Proctection
(IP Protection)
Anti-Debug Methods
Used
CodeMeter Variant
Individual
Encryption of Functions
Integrity Protection
(Tamper Protection)
Authenticity of Software
(Secure Loader / Authenticity)
Java SE
Java EE
Embedded
Operating System
.NETPC (Windows,
Linux, OS X)
CodeMeter
Runtime
CodeMeter
Runtime
CodeMeter
Runtime
CodeMeter
Embedded
CodeMeter
Embedded
IxProtector
AxProtector
AxProtector .NET
AxProtector Java
AxProtector CmE
ExProtector
50

Functions of Protection Suite
 Software authenticity (Secure Load)
 Prevention of the execution of non-validated software
 Integrity Protection (Tamper Protection)
 Detection of changes (in memory!) and reaction
 Automatic Protection (IP Protection)
 Protection against reverse engineering and piracy
 Anti-Debug Methods
 Individual Encryption of Functions
 Encryption at method level

AxProtector
Protected ApplicationCompiled Application
Header
AxEngine
(Security Engine + Public Key)
AxProtector
Encrypted
Code Section
Encrypted
Data Section
Encrypted
Resource Section
Header
Data Section
Resource Section
Code Section
Signature
Private Key
Public Key

Self-Check
Executable
Signature
Check
Signature
(Hash, Public Key,
Signature)
Calculate Hash of the Executable
Error
Yes
No
AxEngine

Check of another Module
Executable Dynamic Link Library
AxEngine
Signature
AxEngine
Signature
exe - exe
exe - dll
dll - dll
dll - exe

AxProtector
[WIBU-SYSTEMS Control File]
...
[Commandline]
...
-cav
...
[CheckCodeIntegrity Dlls]
Image1 = ShowHex.dll
...
Check of
other
modules
Self
Check

ExProtector
 ExProtector = Protection of executable files on embedded operating
systems
 Integration of the "AxEngine" as ExEngine in the loader of the operating
system / boot loader
 Use of signatures and certificates
 Rights Management: Who can sign the applications?

Usage of certificates within
CodeMeter

Secure Firmware Update
 There is a Wibu root certificate
 There are production certificates, derived from the root certificate
 Each CmDongle gets the public root key during production
 Firmware update is signed with a production certificate
 Old firmware checks the update (signature and certificate) before it applies
the new firmware into the CmDongle

CodeMeter Universal Firm Code
 Licenses are signed by the vendor
 Licenses consist of a certificate and an encrypted part
 The license certificate can contain an authorization for license transfer
 In case of transfer, the original certificate is sent through and a new
certificate of the issuing CmContainer is generated
 With CodeMeter, everything is done transparently in the background

Deutschland: +49-721-931720
USA: +1-425-7756900
China: +86-21-55661790
http://www.wibu.com
info@wibu.com
Germany: +49-721-931720
USA: +1-425-7756900
China: +86-21-55661790
http://www.wibu.com
info@wibu.com
Thank you for your attention
Vielen Dank für Ihre Aufmerksamkeit

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