A pretty shocking thing came to light this evening – Lenovo is installing adware that uses a “man-in-the-middle” attack to break secure connections on affected laptops in order to access sensitive data and inject advertising. As if that wasn’t bad enough, they installed a weak certificate into the system in a way that means affected users cannot trust any secure connections they make – TO ANY SITE.
We trust our hardware manufacturers to build products that are secure. In this current climate of rising cybercrime, if you can’t trust your hardware manufacturer, you are in a very difficult position. That manufacturer has a huge role to play in keeping you safe – from releasing patches to update software when vulnerabilities are found to behaving in a responsible manner with the data the collect and the privileged access they have to your hardware.
When bad guys are able to get into the supply chain and install malware, it is devastating. Often users find themselves with equipment that is compromised and are unable to do anything about it. When malware is installed with the access a manufacturer has, it buries itself deep inside the system – often with a level of access that takes it beyond the reach of antivirus or other countermeasures. This is why it is all the more disappointing – and shocking – to find a manufacturer doing this to its customers voluntarily.
Lenovo has partnered with a company called Superfish to install advertising software on it’s customer’s laptops. Under normal circumstances, this would not be cause for concern. However, Superfish’s software has quite a reputation. It is a notorious piece of “adware”, malicious advertising software. A quick search on Google reveals numerous links for pages containing everything from software to remove Superfish to consumers complaining about the presence of this malicious advertising tool.
- Hijacks legitimate connections.
- Monitors user activity.
- Collects personal information and uploads it to it’s servers
- Injects advertising in legitimate pages.
- Displays popups with advertising software
- Uses man-in-the-middle attack techniques to crack open secure connections.
- Presents users with its own fake certificate instead of the legitimate site’s certificate.
This presents a security nightmare for affected consumers.
- Superfish replaces legitimate site certificates with its own in order to compromise the connections so it can inject its adverts. This means that anyone affected by this adware cannot trust any secure connections they make.
- Users will not be notified if the legitimate site’s certificate has been tampered with, has expired or is bogus. In fact, they now have to rely on Superfish to perform that check for them. Which it does not appear to do.
- Because Superfish uses the same certificate for every site it would be easy for another hostile actor to leverage this and further compromise the user’s connections.
- Superfish uses a deprecated SHA1 certificate. SHA1 has been replaced by SHA-256 because attacks against SHA1 are now feasible with ordinary computing hardware. This is insult on top of injury. Not only are they compromising people’s SSL connections but they are doing it in the most cavalier, insecure way possible.
- Even worse, they use crackable 1024-bit RSA!
- The user has to trust that this software which has compromised their secure connections is not tampering with the content, or stealing sensitive data such as usernames and passwords.
- If this software or any of its control infrastructure is compromised, an attacker would have complete and unrestricted access to affected customers banking sites, personal data and private messages.
Below is a photo showing Superfish on an affected laptop presenting a fake certificate instead of the legitimate “Bank of America” certificate. As you can see the user is presented with the fake Superfish certificate instead of the legitimate BoA certificate.
The only way a user would know this has happened is if they check the certificate’s details. Something most ordinary users are unlikely to do to a certificate which to all other appearances is valid and secure.
As mentioned above, the certificate used by Superfish is a deprecated SHA1 certificate that uses 1024-bit RSA. This is particularly obnoxious because they have installed into the system certificates as an unrestricted trusted root certificate. To put it into context, they gave it the same level of trust and authority as Microsoft’s own root certificate. Users affected by this can go to any site on the internet, and so long as it presents this certificate, they will be fooled into thinking they have a secure connection. Since this certificate uses SHA1 it is feasible that an attacker could break it and hijack it. This means an attacker could create a bogus certificate that every one of these users would trust.
This is unbelievably ignorant and reckless of them. Its quite possibly the single worst thing I have seen a manufacturer do to its customer base. At this point I would consider every single one of these affected laptops to be potentially compromised and would reinstall them from scratch.
Lenovo’s response? Typical of companies caught with their hand in the cookie jar, they try to play it down while at the same time saying they have disabled it until it can be “fixed”:
However, it’s hard to see how they could “fix” this software. It’s core functionality undermines the security of SSL rendering the last decade or so of work making the web secure completely irrelevant.
It’s not often that things like this actually get worse. This one has. So, because the man-in-the-middle happens locally, it’s clear that the private key has to be bundled with the software. This is because in order to sign sites on the fly, the software has to do that with the private key.
This is really bad practice. What makes it even worse is that they used a simple dictionary word as the password for the key. After a little reverse engineering, it is possible to extract that key and crack the password. Armed with the private key and its password, you can now sign websites and even software in a way that any affected Lenovo user will trust. What’s worse is you can do it under any fake name that you like. Want to sign a virus so that it looks like legitimate Microsoft software? Go ahead: this will let you do exactly that. Want to set up a fake banking site and pretend to be HSBC? Yup, you can do that too.
Who needs to crack SHA1 or factor RSA-1024 if all you need to do is extract the private key? Game Over.
What was the password they used? Komodia. Both a ridiculously easy dictionary word and the name of a well known manufacturer of SSL products. What’s the betting that they are behind this, and that their own SSL proxy products are designed in a similarly terrifying way?
Read more about the reverse engineering of Superfish on Errata Rob’s Blog –
HOW TO CHECK IF YOU ARE AFFECTED:
My colleague Filippio – @FiloSottile has written a detector for superfish affected laptops. To test if you are affected simply click on the URL below:
WHAT TO DO IF YOU ARE AFFECTED:
Lenovo has published instructions for removing the app:
I have checked them and they are sound BUT they do not provide instructions for removing the malicious certificate in the system certificate store.
To remove the certificate (which is the worst part) follow these instructions:
- Go to Control Panel and search for ‘certificates’.
- You’ll find yourself in Administrative Tools.
- Select “Manage computer certificates” ,
- click on the folder labeled Trusted Root Certification Authorities
- Click on Certificates.
- Find the one labelled “Superfish Inc”, right-click and chose to delete it
HT to @semenko @kennwhite @fugueish on twitter for the screenshots!