Cybersecurity researchers at Sophos have warned that there is a need to identify other adversaries beyond Hafnium that are exploiting bugs to launch attacks, following the reporting of the Microsoft Exchange vulnerabilities and the out-of-band release of security patches earlier this month.

One of such adversaries, which cybercriminals are now using to launch attacks is the discovery of DearCry ransomware, where in an article Sophos noted that DearCry ransomware: “DearCry attacks exploit Exchange server vulnerabilities,”.

The article outlines some new and interesting discoveries about its encryption behavior and more. According to the article headlined by Mark Loman, a ransomware expert at Sophos and director, engineering technology office, the recently-patched set of vulnerabilities in on-premises versions of Microsoft Exchange Server has been actively exploited for over two months.

He said, the exploit initially attributed to a Chinese state-sponsored actor, has now been adopted for a range of cybercrime activities—the latest being ransomware called DearCry.

“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 attached 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 Ryuk, REvil, BitPaymer, Maze and Clop, use ‘in-place’ encryption only,” he said.

He explained that 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.

Hear him: “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”.

The DearCry ransomware, according to the article appears to be created by a beginner, stressing that it is unsophisticated, and does little to hide itself from detection. Its most notable feature is that the encryption header that DearCry adds to the attacked files looks similar to the header used by the notorious WannaCry ransomware, which seems more than a coincidence.


ITPulse is a wholly information technology communication (ICT) news website, with a special focus on the African continent. The website provides up-to-date biz-tech news, analysis and comprehensive and thorough insight into the continent's ICT terrain

Leave A Reply