Pierluigi Paganini July 13, 2012

It’s hacking time! Within a few days we saw two attacks that had disastrous consequences, the victims are prominent Formspring portal and the Yahoo Voices service. The Yahoo branch hacked is Yahoo Contributor Network a sort  of content farm that paid users to publish their submissions.

The Yahoo service allow users to post articles and media such as videos, unfortunately yesterday it has been hacked by the group of hackers called D33DS Company that has stolen and published 453,491 email addresses and passwords in a document  named “Owned and Exposed”.  The file containing the user’s credentials has been widely distributed via BitTorrent and various file lockers on the web.

The D33Ds hackers claim they released the information to show the security leak at Yahoo, and not to realize frauds or for other malicious purposes.

The technique used for the data breach is quite simple, another victim of a SQL Injection attack, the event pose again serious reflection of the security level of the major companies that demonstrate their services too vulnerable to cyber attacks.

The hackers left the following message;

We hope that the parties responsible for managing the security of this subdomain will take this as a wake-up call, and not as a threat.

In this case seems that the user’s credentials were all stored in plain text, if confirmed it explains the responsibilities of the company.

It’s happened to company such as Sony and LinkedIN, firms that we wrongly consider as fortresses. Their approach to security is inadequate and groups of hackers have demonstrated it.

A data breach exposes the user to several risks, the information stolen in fact could be used directly to exploit sensible information or used for further attacks. Risky user’s behaviours, like the use of an unique password for several services on the web, could open the door to a chain of hacks that could create great damage.

Of course the first suggestion for the user of Yahoo Voice is to change his password for all those services that share the same credentials.

The first question to submit to the security managers of Yahoo regarding the incident is related to the password management, how is possible that a so huge quantity of passwords has been leaked and exposed in plain text in a short time?

Which were the defense systems implemented and how is possible that none security audit has discovered the exploited vulnerabilities considering its simplicity?

Following the official statement published by Yahoo:

At Yahoo we take security very seriously and invest heavily in protective measures to ensure the security of our users and their data across all our products. We confirm that an older file from Yahoo Contributor Network (previously Associated Content) containing approximately 450,000 Yahoo and other company users names and passwords was compromised yesterday, July 11. Of these, less than 5 percent of the Yahoo accounts had valid passwords. We are taking immediate action by fixing the vulnerability that led to the disclosure of this data, changing the passwords of the affected Yahoo users and notifying the companies whose users’ accounts may have been compromised. We apologize to all affected users. We encourage users to change their passwords on a regular basis and also familiarize themselves with our online safety tips at security.yahoo.com.

Are we really faced with a catastrophe? which are the risks for all Yahoo users?

It’s clear whose log-in credentials have been stolen but seem highly likely that the exposed info are only related to Yahoo’s contributors that write contents for either Associated Content or Yahoo. The company also added that fewer than 5 percent of the passwords disclosed are currently valid.

Statistics on Yahoo data breach

Of course the huge quantity of credentials stolen could also be used by researchers to elaborate statistics, really interesting the one proposed by ESET and available on PastBin, following an useful extract:

and also  frequency of the various domains used for e-mail addresses

The true mystery

There is also a strange aspect of the data breach that could be considered really worrying, in the list of password revealed by D33Ds groups are contained also credentials there are not belonging to Yahoo but that appear to be related to other e-mail services, including Gmail,  AOL and Hotmail.

Maybe in the past the Associated Content allowed users to use e-mail addresses as their usernames to log-in to the service, a classic example of cross authentication mechanism already targeted in the last months.

To avoid a domino effect it’s strongly suggested to promptly alert those users, their email accounts may have already been compromised.

Pierluigi Paganini

References

http://blog.eset.se/statistics-about-yahoo-leak-of-450-000-plain-text-accounts/