Yomi’s malware engine implements a multi-analysis approach that is able to exploit both: static analysis and behavioral analysis, enjoy it”

Nowadays malware represents a powerful tool for cyber attackers and cyber criminals all around the world, with over 856 million of distinct samples identified during the last year it is, with no doubt, one of the major kinds of threat that companies and organizations are tackling to keep running their business without losing resources, time, money, shares and, last but not least, reputation and customers.



Decades of adversarial coevolution with the Anti-Virus industry led the malware threats to develop the ability to evade detection, bypassing security boundaries and staying silent until the proper time. Finally unleashing their malicious behaviour, enabling remote hackers, cyber-criminals and spies to steal secrets, data, digital goods and money, compromising business processes and even human life. For fun and profit.



This battle, against malware, is huge. Trends and market evolution has shown no single Vendor has the power to overcome these threats, but the cooperation of security professionals, info-sec and intelligence communities, Vendors, CERTs and CSIRTs can.



With this in mind, few months ago Yoroi decided to actively support this Cause sharing proprietary tools to help the Info-Sec community to detect, analyze and dissect malware threats, opening the “Yomi” sandox to the public: the first completely Italian malware analysis sandbox, today extending access to all the community users.



Figure. “Yomi: The Malware Hunter” main interface

The Malware Hunter

Yomi is a malware sandbox able to digest and detonate malicious documents, executables, installers and scripts in a controlled environment, silently recording each samples actions inside the custom analysis environment designed to defeat evasion techniques, and then spot and track the malicious behaviour hidden by attackers.



Yomi’s malware engine implements a multi-analysis approach able to exploit both: static analysis and behavioral analysis. The static analysis section includes document and macro code extraction, import, dependencies and trust chain analysis, while behavioural analysis is weaponized to recognizing malicious (or suspicious) actions the malware silently does, giving also a powerful insight on command and control, exfiltration and lateral movement activities over the network. Each analysis is reported in an intuitive aggregated view to spot interesting patterns at a glance.



Figure. Network connections at a glance

The behavioural detection engine is not only able to detect anomalous, suspicious or malicious actions attempted during the analysis, Yomi has also been designed to help human analysts to understand the dynamic of the malicious code execution, giving detailed visibility of the control flow and interactions the malware performs (“Action Graph”). Yomi technology includes many static and dynamic engines in order to avoid as much as possible Malware evasion.

Figure. Behavioural signatures and action graph example



Yomi can analyse a huge variety of executable file types, ranging from PE32 (Native or .NET) both x86 and x86_64bit, Java binaries, Powershell scripts, JS or VB scripts, Cabinet files, HTML pages, PDF documents, Office Documents such as Powerpoint, Excel or Word files (even the exetic ones) and several common or uncommon compressed archives format ranging

from ZIP, 7z, RAR, TAR, BZ2, up to the ACE format. Yomi provides ad hoc analysis path for each of these file families, leveraging a plethora of security tools to extract much information as possible from each sample. For instance documents and spreadsheets are inspected for macro code or embedded exploits, extracting them from the original file, instead executable files are statically checked to gather contextual info and then instrumented for dynamic analysis, or also Java files, decompiled to ease their manual inspection.

Anyway, stay tuned since we are planning to release many additional features in “Yomi: The Malware Hunter” in the next months.

HTTPS Inspection

Network addresses, domains and patterns are one of the most actionable kinds of indicators a blue team may exploit to spot malicious activity within network perimeter, their relevance can also be appreciated during threat intelligence operations, where they represent some of the basic blocks needed to track threat actors activities.



However, during the years, due to the increasing usage of end to end encryption, attackers started to abuse SSL protected channels to avoid detection, leveraging the limited visibility on these channels to evade IPS and next-gen proxies, enabling them to bypass an important part of the perimetral security controls, leaving the victims in the hand of their last resource: antiviruses. Well known technologies, even by cyber criminals.



Also several automated malware analysis are not equipped to deal with encrypted channels, leaving the effort of the communication inspection to the cyber security analysts. With this in mind, Yoroi choose to empower “Yomi: The Malware Hunter” with SSL inspection capabilities, for free. A cutting edge feature typically available only in premium services, enabling community malware hunters to analyze even the encrypted tunnels malware code sets up, unveiling their hidden data.



In fact, Yomi supports the Man in the Middle feature, able to force eventual malicious samples under analysis to transit into an ad hoc SSL proxy, instrumented to record and analyze network traffic in transit, giving visibility on encrypted channel to the malware hunters.



Figure. Man in the Middle traffic interception

Private Reports

Figure. Private report submission

Almost all security professional knows not every sample and not every analysis can be shared to the public. Some times, especially during APT investigations, analysis reports cannot be disclosed to the community, at least during the initial phases of the analysis, or, for instance, during take-downs or joint investigation with law enforcement, typically requiring some degree of secretiveness, at least until the conclusion of the operations.



Yoroi intimately understand this privacy need coming from many professionals and decided to empower Yomi of a game changing feature: the opportunity to choose to NOT share the analysis with the community, enabling its users to request private reports for the submitted samples. This means both sample and analysis report too will not be disclosed to the community. A feature many times not available in free tools.

Community and Contests

Figure. Custom tags

“Yomi: The Malware Hunter” is not only a freely available automated analysis tool, it’s designed to engage the community and leverage hunter’s experience, enabling them to tag the submitted samples with names, families and contextual enrichments only a human analyst can afford.



Also, Yomi’s community will have the opportunity to participate in malware contests aimed to spot particular threats or engage the community to gather data and discussion about malware trends spotted in the wild.

Figure. Community context banner

And yes, there also will be a special reward for top submitters and contest participants .. So, give a try to “Yomi: The Malware Hunter”, join the community and start hunting malware with us!

If you want to try Yomi: The Malware Hunter please register here!

PS: feedbacks and opinions are welcome (check the “Give a feedback” form).

Pierluigi Paganini

( SecurityAffairs – Yoroi, malware)

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