Compromising a Mail Client

Your entire work life is in your work mail client.
All the people you communicate with – co-workers, friends, family, vendors, customers, colleagues.
Every email you send. Every email you receive. Any files you attach or receive.
If someone can compromise your mail client, they can see all that.
They can save copies of all your emails, data-mine them and use them for whatever purpose they like. They can build a view of your social network, based on who you exchange emails with, and a model of who you are, based on what you talk about.
That companies like Google do this for “free”, advertising supported webmail shouldn’t be much of a surprise by now – but your corporate email system and your work email is secure, right?
What if an attacker were to set up a man-in-the-middle attack on your employees? Install malware on their iPhone, such that all traffic were transparently routed through a proxy server controlled by the attacker?
Or they could use a more email-centric approach, configuring the compromised mail client to fetch mail from an IMAP server controlled by the attacker that took the employees credentials and passed them through to their real corporate IMAP server – that would let the attacker completely control what the compromised user saw in their inbox. As well as being able to read all mail sent to that user, they could silently filter mail, they could deliver new mail to the users inbox directly, bypassing any mail filters or security. They could even modify the contents of email on-the-fly – adding tracking links, redirection URLs or injecting entirely new content into the message.
Similarly, the attacker could route all outbound mail through a man-in-the-middle smarthost that copied the users credentials and used them to send mail on to their real corporate smarthost. As well as being able to read and modify all mail sent the attacker could also use that access to send mail that masqueraded as coming from the user.
Sounds like the sort of thing you’d expect from criminal malware? Not quite. What I’ve just described is Intro, a new product from LinkedIn.
LinkedIn will be asking your users to click on a link to install a “security profile” to their iPhones. If they do, then LinkedIn will have total control over the phone, and will use that to inject their SMTP and IMAP proxies into your users mailstreams. The potential for abuse by LinkedIn themselves is bad enough – I’ve no doubt that they’ll be injecting adverts for themselves into the mailstream, and their whole business is based on monetizing information they acquire about employees and their employers. But LinkedIn have also been compromised in the past, with attackers stealing millions of LinkedIn user credentials – if they can’t protect their own users credentials, I wouldn’t trust them with your employees credentials.
You might want to monitor where your employees are logging in to your servers from – and suspend any accounts that log in from LinkedIn network space.
Edit: Bishop Fox has looked at Intro too, and come to similar conclusions. TechCrunch too.

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Cloudflare and Spamhaus

Spamhaus has been the subject of a lot of discussion the last few weeks. I touched on this a little in June when I blogged that a number of large brands were getting SBL listings.
But big brands are not the only companies with publicly discussed SBL listings.
Cloudflare, the content delivery network that grew out of project honeypot, has a number of SBL listings, covering at least 2 /18s and a /20. Representatives and customers of Cloudflare have been discussing the listings on twitter.
As a content provider, Cloudflare isn’t actually sending mail nor are they actually hosting the content. What they are doing is providing consistent name service and traffic routing to malicious websites. In fact, they’ve been providing services to a malware botnet controller (SBL138291) since May, 2012. They’re also providing services to a number of SEO spammers. Both of these actions are justification for a SBL listing, and Spamhaus has a history of listing providers protecting spammers.
Cloudflare claims they take action on all “properly filed complaints” and they may actually do that. But their reports require quite a bit of information and require consent for releasing information to 3rd parties. Looking at the website, it appears to me to be a site designed to discourage abuse reports and stop people from reporting problems to Cloudflare.
When you look at the Cloudflare business model it’s clearly one that will be abused. Cloudflare acts as a reverse proxy / pass through network that caches data from their customers. This protects the abusers webhosting setup and prevents people tracking the abuser from being able to determine the true host of a website. As a responsible internet citizen, Cloudflare should be disconnecting the customers hiding behind Cloudflare’s services.
Unfortunately, Cloudflare seems unwilling to actually police their customers. They’ve taken a totally hands off approach.
Let’s be frank. Cloudflare has been providing service to Botnet C&C servers for at least two months. It doesn’t matter that the abuser has the malware on a machine elsewhere, Cloudflare’s IP is the one that serves the data. I don’t care what you think about spam, providing service to malware providers is totally unacceptable. It’s even more unacceptable when you claim to be a security company. Nothing about malware is legitimate and the fact that Cloudflare is continuing to host a malware network command and control node is concerning at the very least.
Cloudflare (.pdf) is listed on Spamhaus for providing spam support services. The most obvious of these is providing service to a malware controller. And Spamhaus escalated the listings because they are allowing other abusers to hide behind their reverse proxy.

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Flush your DNS cache (again)

This time it appears that DNS for major websites, including the NY Times, has been compromised. Attackers put in DNS entries that redirected visitors to a malware site. The compromise has been fixed and the fake DNS entries corrected.
However, people may still have the old data in their DNS caches and security experts are suggesting everyone flush their DNS cache to make sure the fake data is gone.
The Washington Post has an article explaining DNS hijacking.

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Browsers, security and paranoia

MAAWG is coming up and lots of us are working on documents, and presentations. One of the recent discussions is what kind of security recommendations, if any, should we be making. I posted a list of things including “Don’t browse the web with a machine running Windows.”
Another participant told me he thought my recommendation to not use a windows machine to browse the web was over the top and paranoid. It may be, but drive by malware attacks are increasing. Visiting big sites may not be enough to protect you, as hackers are compromising sites and installing malware to infect visitors to those sites. Some ad networks have also been used to spread malware.
Criminals have even figured out how to install malware on a machine from email, without the recipient having to click or open attachments.
Avoiding the internet from a machine running Windows is a security recommendation I don’t expect many people to follow, but I do not think security and anti-virus software is enough to protect people from all of the exploits out there.
Of course, there are a lot of reasons that one might be forced to use a particular browser or operating system. For instance, I was on the phone with my bank just today to ask if they supported Safari. They say they do, but there are some things that just don’t work. The customer service rep said that they recommend Internet Explorer to all their users. She then suggested I switch browsers. No thanks, I’ll deal with the broken website.
Compromises are a major threat, and criminals are spending a lot of time and money on creating ways to get past current security. No longer is “not clicking on malware” enough to protect users. When a security clearinghouse is compromised and used as a vector for a targeted attack against Google, none of us are safe. When a security company is compromised, none of us are safe.
I realize my recommendation to avoid browsing the web on a Windows based machine is more wishful thinking than practical. I also know that other browsers and operating systems will be targeted if enough people move away from currently vulnerable operating systems. And I know that a simple, offhand suggestion won’t fix the problem.
As someone who’s been online long enough to see the original Green Card spam I know that online dangers evolve. But I can’t help thinking that most of us aren’t taking the current threats seriously enough.

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