Why you should not trust your Digital Certificates

  • David Gee (CSO Online)
  • 26 August, 2015 10:25

As humans have always used a physical signature as a method to provide a verification of identity. Hence we sign contracts and in the past we used our (John Hancock) signature to access our bank accounts. If I have a signed document, then it is attributed a degree of trust.

On the internet we have adopted Digital Certificates to provide a similar level of assurance. This entails a 3rd party organisation that issues a certificate and having this provides a proof point of your identity. By this very act we have entrusted someone else to provide this verification as a service. But let's realise that these Certificate Authorities are not all the same.

Each issuing authority is different organisation, cost structures and the actual price of the certificate can have large variance. Moreover, each organisation own approach to security can also have dramatic variance. It is not surprisingly therefore that you can't really trust a Digital Certificate.

Who do you trust?

You want to use a Certificate Authority that has a good track record of securing their own systems. This means that due diligence is required to ensure that they robust security and processes. Plus that they haven’t issued improper certificates in the past.

We trust a Certificate and the implication of this trusted position; is the belief that it does not include any malicious code. This has resulted in the increased attractiveness for Cyber intruders to invest time to have their malicious code signed by a ‘trusted’ certificate

Once the cybercriminals have gained access to the network of software manufacturer’s, they can introduce a malicious file into the build and hence the threat of a valid certificate with risky intent.

This has led to some of the largest organisations such as Google having their share of incidents. Even organisations like China Internet Network Information Center (CNNIC) have been implicated around concerns around some cyber attacks.

Man in the Middle

On the internet, we communicate with others through many tools and channels. We inherently trust that the connection is secure and unless we see or hear something suspicious, and we will share our most personal and private information.

Our messages from A to B, clearly are addressed to usually people that we know. If your digital certificate is compromised through a 'Man in the Middle' attack, where we think we are talking to B, but actually these messages are being relayed to C. This alone can be a high risk, and then let's not forget that C can also change the message that you receive.

Trust the Certificate?

This internet that we use everyday has been established using Public Key infrastructure PKI as the foundation of trust. In reality every PC connected has a list of trusted root Certificate Authorities. In turn this has led to a 'chain of trust'.

In Banking apps we operate with a secure connection where there is a signed file is “trusted”. A digital certificates is used to secure websites and also to secure email. When a browser is confronted with a HTTPS server with an untrusted server certificate, it will generate an immediate warning.

The problem is that the assumption is that we have entrusted the Certifying Authority to only issue certificated to appropriate users. There are many documented examples of organisations that have by possession of a certificate have been able to mount a man in the middle attack.

In effect ownership of a certificate provides a scenario that the system is seen as valid. Which in normal cases is exactly as designed. The problem is when this falls into the wrong hands.

Gaps in Process and System create risk

Each Certificate Authority has to maintain vigilance and ensure that their systems are secured. Their own internal processes also need to be robust, and therefore only issue certificates to validated parties. This process could include some element of second and third factor authentication so that only registered email addresses or phone numbers can request certificates.

At the end of the day, this can be susceptible to the human factor and we know that this can result in variance to what is supposed to happen. We all trust our fellow humans to a different degree and I think we have to also use that same judgment when it comes to different Digital Certificates and the organisations that we process these.

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