CryptoDefense ransom malware using Java drive-by exploit to boost infection rate

Email attachments not the only distribution method, says Bromium

The gang behind the CryptoDefense ransom malware has been distributing it using a simple Java drive-by attack as a way of boosting the number of victims, security firm Bromium has confirmed after analysing a version that appeared in March.

Although less well known than the rival CryptoLocker, CryptoDefense is more than a mere copycat program and shows an evolution beyond the former's incredibly successful design.

As well as employing powerful RSA-2048 bit encryption to scramble the victim's data, CryptoDefense targets source code as well as conventional data files, bypassing Windows Defender (in Windows 8) and disabling shadow and Windows restore to make it impossible to reinstate the files using that option.

A curious feature is that the gang behind CryptoDefense extended the 48-hour deadline to pay for an encryption key to as long as several weeks, presumably in a ploy to raise the number of people willing to pay.

When Symantec first documented the malware in March, its main distribution method was via email attachments, but that seems to have been complemented with more dangerous drive-by downloads targeting Java CVE-2012-4681 from 2012, which affects Java 7, update 6.

Bromium's analysis confirms that, as with Cryptolocker, drive-by infections have all along been a major way of infecting users. This might explain its success.

The stealthiness of drive-by attacks is that they usually require no user interaction and don't ask the user to click on a link or open an attachment. The example picked apart by Bromium didn't even require a privilege elevation, writing its code into a new process rather than piggybacking on one already running.

The malware's designers did make one major error that renders some earlier CryptoDefense infections reversible; the key used to encrypt files remains on the user's hard drive. Unfortunately, a version fixing this oversight has since appeared so the recovery instructions on crypto authority site Bleeping Computer won't work for everyone.

Exactly where Windows users stand in relation to this kind of malware is hard to assess. The element of surprise has gone for ransomware attackers and some have moved hack to conventional social engineering, rather than technically elaborate symmetric encryption keys to fuel their strong-arming.

Others seem to be morphing the attack concept to mobile devices, with variants on the idea now targeting Android and (through an attack on Apple's iCloud service) even the iPhone and iPad.

Join the CSO newsletter!

Error: Please check your email address.

Tags Personal TechsymantecsecurityBromium

More about AppleRSASymantec

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by John E Dunn

Latest Videos

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

  • 150x50

    IDG Live Webinar:The right collaboration strategy will help your business take flight

    Speakers - Mike Harris, Engineering Services Manager, Jetstar - Christopher Johnson, IT Director APAC, 20th Century Fox - Brent Maxwell, Director of Information Systems, THE ICONIC - IDG MC/Moderator Anthony Caruana

    Play Video

More videos

Blog Posts