Rombertik malware destroys computers if detected

Rombertik is designed to steal any plain text entered into a browser window

A new malware program designed to steal plain text entered into a web browser, Rombertik, will in some instances destroy a computer's Master Boot Record if detected by security software.

A new malware program designed to steal plain text entered into a web browser, Rombertik, will in some instances destroy a computer's Master Boot Record if detected by security software.

A new type of malware resorts to crippling a computer if it is detected during security checks, a particularly catastrophic blow to its victims.

The malware, nicknamed Rombertik by Cisco Systems, is designed to intercept any plain text entered into a browser window. It is being spread through spam and phishing messages, according to Cisco's Talos Group blog on Monday.

Rombertik goes through several checks once it is up and running on a Windows computer to see if it has been detected.

That behavior is not unusual for some types of malware, but Rombertik "is unique in that it actively attempts to destroy the computer if it detects certain attributes associated with malware analysis," wrote Ben Baker and Alex Chiu of the Talos Group.

Such "wiper" malware has been used in the past, notably against South Korean targets in 2013 and against Sony Pictures Entertainment last year, an attack attributed to North Korea by the U.S. government.

The last check Rombertik does is the most dangerous one. It computes a 32-bit hash of a resource in memory, and if either that resource or the compile time had been changed, Rombertik triggers self-destruct.

It first takes aim at the Master Boot Record (MBR), the first sector of a PC's hard drive that the computer looks to before loading the operating system. If Rombertik doesn't have access to the MBR, it effectively destroys all of the files in a user's home folder by encrypting each with a random RC4 key.

Once either the MBR or the home folder has been encrypted, the computer restarts. The MBR enters an infinite loop that stops from computer from rebooting. The screen reads "Carbon crack attempt, failed."

When it first gets installed on a computer, it unpacks itself. Around 97 percent of the content of the unpacked file is designed to make it look legitimate and is composed of 75 image and 8,000 decoy functions that are actually never used.

"This packer attempts to overwhelm analysts by making it impossible to look at every function," Talos wrote.

It also tries to avoid sandboxing, or the practice of isolating code for a while until it has checked out. Some malware tries to wait out the period it is in a sandbox, hoping the sandbox period will time out and it can wake up.

Rombertik stays awake, however, and writes one byte of data to memory 960 million times, which complicates analysis for application tracing tools.

"If an analysis tool attempted to log all of the 960 million write instructions, the log would grow to over 100 gigabytes," Talos wrote.

Send news tips and comments to Follow me on Twitter: @jeremy_kirk

Join the CSO newsletter!

Error: Please check your email address.

Tags Cisco Systemssecuritymalware

More about CiscoSony

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Jeremy Kirk

Latest Videos

  • 150x50

    CSO Webinar: Will your data protection strategy be enough when disaster strikes?

    Speakers: - Paul O’Connor, Engagement leader - Performance Audit Group, Victorian Auditor-General’s Office (VAGO) - Nigel Phair, Managing Director, Centre for Internet Safety - Joshua Stenhouse, Technical Evangelist, Zerto - Anthony Caruana, CSO MC & Moderator

    Play Video

  • 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

More videos

Blog Posts

Market Place