world exit download Cross icon Menu icon

We have seen a recent increase in malware activity and would like to provide additional information on what has been discovered at this time. Please find below a more detailed investigation into the behavior and mitigation methods applicable to CryptoWall 3.0, Dridex and Dyre/Dyreza malware variants.

What We Know

Behavior of Cryptowall 3.0:

- The latest version of this malicious software is spread mainly via Spam email containing the CryptoWall executable as a ZIP file attachment or as drive-by download attacks facilitated by web browser exploit kits like Angler and Magnitude.

- The result of a CryptoWall infection is having data files on the local system and any connected network file shares encrypted with a strong public-key cipher.

- The only ways to recover the encrypted files is to restore them from a recent backup or to pay the ransom demanded by the cybercriminals in exchange for the decryption key (the ransom amount is reported to be between 2–4 Bitcoin).

Behavior of Dridex:

- Dridex is a banking Trojan designed to steal financial information such as online banking credentials from victims.

- Commonly-seen threat spreading mainly via spam email.

- The usual method of infection is an attached Microsoft Word document containing an embedded macro that downloads and executes the Dridex malware.

- Social engineering techniques are used to get the victim to enable Microsoft Office macros in order to execute the malicious script. 

Behavior of Dyre/Dyreza:

- This banking trojan is designed to hook into the victim's web browser and capture online banking credentials as they are typed in by the victim.

- The usual method of infection is via spam email containing malicious attachments or phishing emails containing links to web browser exploit kits that install the malware on the victim's computer.

- Victim must open attachments or visit the links with a vulnerable browser in order to get infected.

eSentire Defenses

eSentire features that help protect you include:

- Executioner can stop the download of malicious payloads over HTTP if you have instructed ESOC to enable it.

- AMP can stop the communication to known command and control servers.

- Behavioral analysis tools can detect anomalous network behavior.

- The ESOC can quarantine suspected systems at your direction or based on established policy.

Further Protection:

In the past 18 months, eSentire has released at least three advisories regarding Cryptolocker/Cryptowall.  If the mitigation steps detailed in the advisories have not been performed, we strongly recommend that they be implemented as soon as possible.

However, in general, we recommend that you: 

- Do not enable Microsoft Office macros in order to view documents received via unsolicited email.

- Regularly back up your important files to an offline data store that is not usually accessible from the local system.

- Never open attachments or click on URL links in unsolicited email.

- Use a tool such as Qualys BrowserCheck (browsercheck.qualys.com) to keep your web browser software and plugins updated with the latest security patches.

- Utilize browsers extensions that intercept third party application requests through the browser (for example, Flashblock for Chrome).

- Run ad-blocker software or strip out ad networks at the network level (via Proxies/DNS Sinkhole)

- Utilize exploit protection tools like Malwarebytes Anti-Exploit or EMET to stop the exploitation of your browsers/plugins.

- Implement anti-execute technologies such as AppLocker to prevent binary malware payloads from executing.

Resources

esentire.com/news-and-events/security-advisories/ransomware-variant-cryptofortress-advisory/

esentire.com/news-and-events/security-advisories/fin4/

 

See the latest security advisories

Articles and reports written by eSentire staff and our Threat Intelligence Research Group.

Ready to get started?
We're here to help.

Get Started
Reach out to schedule a meeting and learn more about our Managed Detection and Response, Risk Advisory, and Managed Prevention capabilities.