What to avoid in Dropbox-related phishing attack

Corporate employees familiar with Dropbox should take extra precautions to avoid becoming a victim of a phishing attack that uses the popular file-sharing service.

Cybercriminals have been sending out emails with malicious links pointing to a ZIP file on Dropbox that contains a screensaver that is actually ransomware similar to one known as CryptoLocker, security vendor PhishMe reported Friday.

[Brown HIV researchers make Dropbox secure with nCrypted Cloud]

The attackers try to trick the recipients into clicking on the link through a variety of ploys, including disguising the email, so that the link appears to point to an invoice or a fax report or message.

If someone receives the email at work, "they may think that they're receiving a fax and it's something they need to look at, which makes them inclined to go ahead and open it," Ronnie Tokazowski, senior researcher at PhishMe, said.

Clicking on the link to the ZIP file and then the screensaver file inside launches the malware that encrypts files on the victim's hard drive. PhishMe estimates that victims have had as many as 20,000 files encrypted. Files typically affected by such ransomware include documents, archive files, executables and JPEGs.

Once executed, the malware launches a page on the victim's default browser, demanding that $500 in Bitcoins be deposited in the criminals' electronic wallet. Failing to do so after a certain amount of time leads to the ransom doubling to $1,000.

Based on an examination of three of the attackers' wallets, the scammers have collected at least $62,000, Tokazowski estimates. The ransom demand and payment transactions are conducted over the Tor anonymity network.

The attack does not exploit a vulnerability on Dropbox. PhishMe had not discussed the phishing campaign with Dropbox, which did not respond to a request for comment.

PhishMe discovered the scam after its own employees received the phishing emails, Tokazowski said. Almost 20 of the company's 50 employees received the messages.

PhishMe does not believe it was directly targeted in the campaign, but was just one of many companies whose employees might have received the emails.

[Box, Dropbox, or drop both?]

"There's been no evidence that they (the attackers) have been specifically going after us," Tokazowski said.

To avoid becoming a victim, companies should advise employees to be wary of downloading ZIP files and emails like the ones described above that have no recognizable sender.

Join the CSO newsletter!

Error: Please check your email address.

Tags dropboxsecurityCryptolockerphishmelegalransomwaremalwarephishing attackcybercrime

More about Dropbox

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Antone Gonsalves

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