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Microsoft hack: Cybercriminals launch DearCry Ransomware – Sophos

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DearCry ransomware 1

Cybersecurity experts are working around the clock to patch systems and shore up networks affected by recent hack of Microsoft’s Exchange email service — an attack that has impacted hundreds of thousands of organizations worldwide.

On Friday, the White House urged victims to patch systems and stressed the urgency: The window for updating systems could be measured in “hours, not days,” a senior administration official said.

“This is a crazy huge hack,” Christopher Krebs, former director of the U.S. Cybersecurity and Infrastructure Security Agency (CISA), tweeted last week.

In that line too, security researchers at Sophos have started to identify other adversaries beyond Hafnium exploiting these bugs to launch attacks.

According to Sophos’ findings, one of these adversaries is DearCry ransomware.  The firm has gone ahead to publish an analysis of samples of DearCry ransomware: “DearCry attacks exploit Exchange server vulnerabilities,”

In the article, TechEconomy.ng found some new and interesting discoveries about its encryption behavior and more.

Some of the key findings are summarized in the following comment from a Ransomware Expert at Sophos and Director, Engineering Technology Office, Mark Loman:

Mark Loman

Mark Loman

Our analysis of DearCry ransomware samples has uncovered a rare encryption attack behavior: a ‘hybrid’ approach. The only other ransomware I’ve investigated over the years that employed a hybrid approach was WannaCry, and this was auto spreading rather than human operated like DearCry. Both first create an encrypted copy of the attacked file, an approach we call ‘copy’ encryption, and then overwrite the original file to prevent recovery, what we call ‘in-place’ encryption. ‘Copy’ ransomware allows victims to potentially recover some data. However, with ‘in-place’ encryption, recovery via undelete tools is impossible. Notorious human-operated ransomware like RyukREvil, BitPaymer, Maze and Clop, use ‘in-place’ encryption only. 

“There are a number of other similarities between DearCry and WannaCry, including the names and the header added to encrypted files. These do not automatically link DearCry to WannaCry’s creator. DearCry’s code, approach and abilities differ significantly from WannaCry; it does not use a command-and-control server, has an embedded RSA encryption key, shows no user interface with a timer and – most importantly – does not spread itself to other machines on the network.

“We found a number of other unusual DearCry characteristics, including the fact that the ransomware actor has been creating new binaries for new victims. The list of file types targeted has evolved from victim-to-victim too. Our analysis further shows that the code does not come with the kind of anti-detection features you would normally expect with ransomware, like packing or obfuscation. These and other signs suggest that DearCry may be a prototype, possibly rushed into use to seize the opportunity presented by the Microsoft Exchange Server vulnerabilities, or created by less experienced developers.

“Defenders should take urgent steps to install Microsoft’s patches to prevent exploitation of their Exchange Server. If this is not possible, the server should be disconnected from the internet or closely monitored by a threat response team,” Mark Loman, explained.

Sophos Intercept X

Sophos Intercept X

YOU MAY ALSO LIKE: Sophos Intercept X and Sophos Intercept X with EDR detect and protect against DearCry ransomware.

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2 Comments

2 Comments

  1. Pingback: Microsoft Hack: Cybercriminals Launch DearCry Ransomware – Sophos | Techvalley

  2. Pingback: Sophos survey shows ransomware recovery cost reaches nearly $2 million - GISTCLIP

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