During a normal monitoring activity, one of the detection tools hits a suspicious email coming from the validtree.com domain. The domain was protected by a Panama company to hide its real registrant and this condition rang a warning bell on the suspected email so that it required a manual analysis in order to investigate its attachment. Digging into this malicious artifact opened up to a possible raising interest of the infamous TA505 in System Integrator Companies (companies in which have been found that threat).
During the past few weeks suspicious emails coming from the validtree.com domain was detected: they were addressing System Integration Companies. The domain validtree.com is registered through namecheap.com on 2017-12-07T15:55:27Z but recently renewed on 2019-10-16T05:35:18Z. The registrant is protected by a Panama company named WhoisGuard which hides the original registrant name. Currently the domain points to 126.96.36.199 which is an IP address assigned to LeaseWeb a VPS hosting provider located in Netherland, Europe. Attached to the email a suspicious word document was waiting to be opened from the victim.
|Brief Description||Document Dropper|
By opening the word document the victim displays the following text (Image1). The document tempts the victim in enabling the macro functionality in order to re-encode the document with readable charsets by translating the current encoding charset to the local readable one.
It was nice to read the obfuscated code since the variable names
Building a re-directors or proxy chains is quite useful for attackers in order to evade Intrusion Prevention Systems and/or protections infrastructures based upon IPs or DNS blocks. In such a case the redirection script pushes to one of the following domains by introducing the HTML meta “refresh” tag, pointing the browser URL to a random choice between 4 different entries belonging to the following two domains:
The used infrastructure, by analyzing the dropping urls, looks like an old infrastructure used for propagating Ransomware. Indeed it’s possible to observe many analogies with the following dropping urls belonging to a previously utilized Ransomware threat:
The infrastructure used in the attacks suggests the involvement of the cybercrime group TA505. The TA505 group, that is known to have operated both the Dridex and Locky malware families, continues to make small changes to its operations. TA505 hacking group has been active since 2014 focusing on Retail and banking sectors.
Recently security experts at Proofpoint observed the notorious TA505 cybercrime group that has been using a new RAT dubbed SDBbot, it is a backdoor that is delivered via a new
Unfortunately, I was not able to analyse the final payload of the attack chain that was still not available at the time of the analysis. The final stage malware analysis is essential to attempt to attribute the attack to a specific threat actor. The evidence and artifacts collected in this analysis suggest two possible scenarios:
An interesting Maldoc acting as drop-and-execute was identified and spotted in the wild targeting System Integrator based in Europe . From the described analysis we attempted to identify the attacker by observing he was exploiting an old infrastructure behind
188.8.131.52 as a dropping websites.
During the analysis time the attack-path was still incomplete and the attacker didn’t weaponize the dropping websites yet, but the spread document is able to grab content from specific URLs and to run directly on the victim machine.
The used strings for obfuscating the dropper were actually fun and “thematic”. For example strings like “madrillus”, “vulcano”, “pastorale”, “quetzalcoatl” remind an ancient culture (mandrillus, vulcano and quetzalcoatl) while objects like “emotionless” assigned to a specific programming language reminds a witty attacker.
Since no final stage was obtained so far, attribution is quite hard, but TTPs suggest a TA-505 attacker, due to the collected artifacts and to the analyzed URLs.
Additional information, including indicators of compromise (IoCs)
About the author: Marco Ramilli, Founder of Yoroi
I am a computer security scientist with an intensive hacking background. I do have a MD in computer engineering and a PhD on computer security from University of Bologna. During my PhD program I worked for US Government (@ National Institute of Standards and Technology, Security Division) where I did intensive researches in Malware evasion techniques and penetration testing of electronic voting systems.
I do have experience on security testing since I have been performing penetration testing on several US electronic voting systems. I’ve also been encharged of testing uVote voting system from the Italian Minister of homeland security. I met Palantir Technologies where I was introduced to the Intelligence Ecosystem. I decided to amplify my cyber security experiences by diving into SCADA security issues with some of the most biggest industrial aglomerates in Italy. I finally decided to found Yoroi: an innovative Managed Cyber Security Service Provider developing some of the most amazing cyber security defence center I’ve ever experienced ! Now I technically lead Yoroi defending our customers strongly believing in: Defence Belongs To Humans
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(SecurityAffairs – TA505, cybercrime)