Compromised Yahoo! accounts continue to spread Android malware

Posted by   Virus Bulletin on   Jun 24, 2013

Problem likely to be on Yahoo!'s side.

In recent weeks, we have noticed an uptick in the amount of spam sent from compromised Yahoo! accounts; we have reasons to believe the problems are on Yahoo!'s side, rather than that of its users'.

Spam sent from compromised accounts is notoriously hard to filter: the sender is not only legitimate, they also tend to be a regular correspondent of the recipient. To make matters worse from a filter's point of view, the contents of these particular emails is little more than a link to a URL hosted on a legitimate, but compromised, website.

When opened in a regular browser, the link sends the user to a website spamvertising a health-related product, which is mildly annoying and time-wasting. However, when opened on an Android device, it downloads a variant of the 'NotCompatible' trojan.

We have written about this before, and not much appears to have changed since. There is still little obfuscation used, other than a JavaScript-based redirect on the destination website, and the malware doesn't appear to check the IP address from which the request is made.

While the links are all hosted on compromised websites (we found them running vulnerable versions of Joomla or WordPress), the payload is found on a number of recently registered domains, which appear to have been set up for this purpose:
  official.androidsecurityhealth.ru
  official.androidsecurityadded.ru
  official.androidsecurityrow.ru
  official.androidsecurityfix.ru   official.androidsecuritydata.ru

We have contacted the registrar where the domains were registered anonymously - but so far have received no response. The domains are still active and are serving malware from either 46.19.139.21 or 46.19.139.22.

But there is something else about these spam emails that is remarkable: they were all sent from legitimate Yahoo! accounts, to addresses in the users' contact list.

I have worked in the industry for long enough to know that end-users tend to be the most vulnerable component of any system. They use insecure passwords, get infected with keyloggers, or simply don't treat their passwords as confidential - all of which can lead to someone else hijacking the account.

However, we have reasons to believe that, in this case, the problem lies on Yahoo!'s side.

Firstly, the volume of spam from compromised Yahoo! accounts is significantly larger than that sent from other webmail providers. We have noticed this before - and, if anything, the problem has since become worse.

More importantly, from various reliable sources, we know that accounts that had not been used for a very long time have been compromised as part of this campaign. Including, somewhat embarrassingly, an account of my own.

That account was a throw-away account, which hadn't been used for over a year. I don't remember what the password was, but given the throw-away nature of the account, it may not have been very strong. However, other accounts with strong passwords have been compromised too, making it less likely that the compromises happened through cracking insecure passwords.

The email alert that Yahoo! sent me does suggest that the attackers used a valid password to get in. Whether this was the original password is unclear.

It is unlikely that Yahoo! is unaware of some issues on its side, and the fact that the issue has not yet been resolved suggests that the solution isn't easy to find. It is not even clear whether two-factor authentication will help against these attacks, though it is likely that it will, and setting it up is a good idea.

Yahoo! Mail has come under criticism from the security community recently, both for still not offering HTTPS by default and because of a rather ill-advised plan to make email addresses that had not been used for a year available for registration. But Yahoo! also provides email services for millions of happy customers all over the world. It owes it to them, and to the wider Internet community, to prevent acounts from being taken over.

We will continue to follow the matter closely and are happy to be contacted by Yahoo! to share the samples of spam we have seen.

Posted on 24 June 2013 by Martijn Grooten

twitter.png
fb.png
linkedin.png
hackernews.png
reddit.png

 

Latest posts:

VB2019 paper: APT cases exploiting vulnerabilities in region-specific software

At VB2019, JPCERT/CC's Shusei Tomonaga and Tomoaki Tani presented a paper on attacks that exploit vulnerabilities in software used only in Japan, using malware that is unique to Japan. Today we publish both their paper and the recording of their…

New paper: Detection of vulnerabilities in web applications by validating parameter integrity and data flow graphs

In a follow-up to a paper presented at VB2019, Prismo Systems researchers Abhishek Singh and Ramesh Mani detail algorithms that can be used to detect SQL injection in stored procedures, persistent cross-site scripting (XSS), and server‑side request…

VB2020 programme announced

VB is pleased to reveal the details of an interesting and diverse programme for VB2020, the 30th Virus Bulletin International Conference.

VB2019 paper: Cyber espionage in the Middle East: unravelling OSX.WindTail

At VB2019 in London, Jamf's Patrick Wardle analysed the WindTail macOS malware used by the WindShift APT group, active in the Middle East. Today we publish both Patrick's paper and the recording of his presentation.

VB2019 paper: 2,000 reactions to a malware attack – accidental study

At VB2019 cybercrime journalist and researcher Adam Haertlé presented an analysis of almost 2000 unsolicited responses sent by victims of a malicious email campaign. Today we publish both his paper and the recording of his presentation.

We have placed cookies on your device in order to improve the functionality of this site, as outlined in our cookies policy. However, you may delete and block all cookies from this site and your use of the site will be unaffected. By continuing to browse this site, you are agreeing to Virus Bulletin's use of data as outlined in our privacy policy.