Netskope debuts as a Leader in the 2024 Gartner® Magic Quadrant™️ for Single-Vendor Secure Access Service Edge Get the report

close
close
  • Why Netskope chevron

    Changing the way networking and security work together.

  • Our Customers chevron

    Netskope serves more than 3,400 customers worldwide including more than 30 of the Fortune 100

  • Our Partners chevron

    We partner with security leaders to help you secure your journey to the cloud.

A Leader in SSE.
Now a Leader in Single-Vendor SASE.

Learn why Netskope debuted as a leader in the 2024 Gartner® Magic Quadrant™️ for Single-Vendor Secure Access Service Edge

Get the report
Customer Visionary Spotlights

Read how innovative customers are successfully navigating today’s changing networking & security landscape through the Netskope One platform.

Get the eBook
Customer Visionary Spotlights
Netskope’s partner-centric go-to-market strategy enables our partners to maximize their growth and profitability while transforming enterprise security.

Learn about Netskope Partners
Group of diverse young professionals smiling
Your Network of Tomorrow

Plan your path toward a faster, more secure, and more resilient network designed for the applications and users that you support.

Get the white paper
Your Network of Tomorrow
Introducing the Netskope One Platform

Netskope One is a cloud-native platform that offers converged security and networking services to enable your SASE and zero trust transformation.

Learn about Netskope One
Abstract with blue lighting
Embrace a Secure Access Service Edge (SASE) architecture

Netskope NewEdge is the world’s largest, highest-performing security private cloud and provides customers with unparalleled service coverage, performance and resilience.

Learn about NewEdge
NewEdge
Netskope Cloud Exchange

The Netskope Cloud Exchange (CE) provides customers with powerful integration tools to leverage investments across their security posture.

Learn about Cloud Exchange
Netskope video
The platform of the future is Netskope

Intelligent Security Service Edge (SSE), Cloud Access Security Broker (CASB), Cloud Firewall, Next Generation Secure Web Gateway (SWG), and Private Access for ZTNA built natively into a single solution to help every business on its journey to Secure Access Service Edge (SASE) architecture.

Go to Products Overview
Netskope video
Next Gen SASE Branch is hybrid — connected, secured, and automated

Netskope Next Gen SASE Branch converges Context-Aware SASE Fabric, Zero-Trust Hybrid Security, and SkopeAI-powered Cloud Orchestrator into a unified cloud offering, ushering in a fully modernized branch experience for the borderless enterprise.

Learn about Next Gen SASE Branch
People at the open space office
Designing a SASE Architecture For Dummies

Get your complimentary copy of the only guide to SASE design you’ll ever need.

Get the eBook
Make the move to market-leading cloud security services with minimal latency and high reliability.

Learn about NewEdge
Lighted highway through mountainside switchbacks
Safely enable the use of generative AI applications with application access control, real-time user coaching, and best-in-class data protection.

Learn how we secure generative AI use
Safely Enable ChatGPT and Generative AI
Zero trust solutions for SSE and SASE deployments

Learn about Zero Trust
Boat driving through open sea
Netskope achieves FedRAMP High Authorization

Choose Netskope GovCloud to accelerate your agency’s transformation.

Learn about Netskope GovCloud
Netskope GovCloud
  • Resources chevron

    Learn more about how Netskope can help you secure your journey to the cloud.

  • Blog chevron

    Learn how Netskope enables security and networking transformation through security service edge (SSE)

  • Events and Workshops chevron

    Stay ahead of the latest security trends and connect with your peers.

  • Security Defined chevron

    Everything you need to know in our cybersecurity encyclopedia.

Security Visionaries Podcast

The Convergence of CIO & CISO Roles
Join host Max Havey on the latest episode of Security Visionaries as he sits down with guest Jadee Hanson, CISO at Vanta.

Play the podcast
The Convergence of CIO & CISO Roles
Latest Blogs

Read how Netskope can enable the Zero Trust and SASE journey through security service edge (SSE) capabilities.

Read the blog
Sunrise and cloudy sky
SASE Week 2023: Your SASE journey starts now!

Replay sessions from the fourth annual SASE Week.

Explore sessions
SASE Week 2023
What is SASE?

Learn about the future convergence of networking and security tools in today’s cloud dominant business model.

Learn about SASE
  • Company chevron

    We help you stay ahead of cloud, data, and network security challenges.

  • Leadership chevron

    Our leadership team is fiercely committed to doing everything it takes to make our customers successful.

  • Customer Solutions chevron

    We are here for you and with you every step of the way, ensuring your success with Netskope.

  • Training and Certification chevron

    Netskope training will help you become a cloud security expert.

Supporting sustainability through data security

Netskope is proud to participate in Vision 2045: an initiative aimed to raise awareness on private industry’s role in sustainability.

Find out more
Supporting Sustainability Through Data Security
Thinkers, builders, dreamers, innovators. Together, we deliver cutting-edge cloud security solutions to help our customers protect their data and people.

Meet our team
Group of hikers scaling a snowy mountain
Netskope’s talented and experienced Professional Services team provides a prescriptive approach to your successful implementation.

Learn about Professional Services
Netskope Professional Services
Secure your digital transformation journey and make the most of your cloud, web, and private applications with Netskope training.

Learn about Training and Certifications
Group of young professionals working

Anatomy of a Ransomware Attack: Cerber Uses Steganography to “Hide in Plain Sight”

Jun 30 2016
Tags
Cloud Best Practices
Cloud Malware
Cloud Security
Netskope Threat Research Labs
Office 365 Security
Ransomware
Tools and Tips
Vulnerability Advisory

Ransomware is a hot topic and it’s about to become hotter. Why? Because now it’s targeting our cloud services. Nearly one out of five malware detections in the past month in the Netskope Active Platform are document files such as Microsoft Word that contain macros. Earlier this week, cloud platform vendor Avanan blogged about a widespread ransomware attack, called Cerber, that is being spread via cloud productivity platform, Microsoft Office 365. Incidentally, we have seen these types of macro-type malware-delivered ransomware across a variety of cloud-based file-sharing apps, and we don’t believe there’s anything necessarily unique about detecting it in Office 365. The name Cerber is derived from Cerberus, a 3-headed dog that guards the entrance to Hades in Greek mythology.

Fig 1 - Cerber ransomware

Figure 1: Image from Cerber ransomware note

The attacks use a decoy document loaded with malicious macro code that downloads Cerber malware files to users’ machines. When the decoy document is opened, it drops a VBScript file (.vbs) with a random name in the format “%APPDATA%\%RANDOM%.vbs.” The VBScript file is then launched using wscript.exe, which downloads an image file named “mhtr.jpg.” This jpeg image is downloaded from the URLs solidaritedeproximite[.]org/mhtr.jpg, 92.222.104[.]182/mhtr.jpg. If the file is not found when visiting solidaritedeproximite[.]org, it will be fetched from 92[.]222[.]104[.]182 as shown in Figure 2 below. At the time of writing this blog, solidaritedeproximite[.]org was not serving the file and was instead delivered from 92[.]222[.]104[.]182.

Figure 2 - cerber ransomewareFigure 3 - cerber ransomeware

Figure 2: Network packet capture displaying attempts to the URLs used to download mhtr.jpg

The image file mhtr.jpg looks benign and displays content related to “zen-coding,” as shown in Figure 3, but has steganographically (hidden in plain sight) embedded malware inside it which is decoded to an exploit as shown in Figure 4. This technique has been used by such historic malware families as Bredolab, but is seeing a resurgence as it permits executables to be transmitted without causing network monitoring devices to suspect malicious activity.

Fig 3 - cerber ransomeware

Figure 3: Image that would be displayed if someone opened mhtr.jpg

Fig 3b - Cerber Ransomeware

Fig 4 - Cerber Ransomware

Figure 4: JFIF image and the encoded blob of mhtr.jpg

At the time of writing this blog, very few security vendors were detecting this image file as shown from the VirusTotal page in Figure 5.

Fig 5- Cerber ransomeware

Figure 5: mhtr.jpg sample detection in VirusTotal

In the next stage of the attack, a random name .exe binary is dropped in %APPDATA% in a hidden folder. In our observation, it was EFSUI.EXE as shown in Figure 6. This is detected by majority of the security vendors as referenced from the VirusTotal page.

Fig 6- Cerber ransomeware

Figure 6: Binary extracted from mhtr.jpg detection in VirusTotal

This binary is a NSIS installer that has a list of files that are also dropped in %APPDATA% as shown in Figure 7.

Fig 7- Cerber ransomeware

Figure 7: Files inside the NSIS installer

The manually extracted payload (MD5 – DB073371DCBAC628E69C2B91E1E18BD9) of the Cerber ransomware is present inside the NSIS installer. Figure 8 shows the count of current security vendors from VirusTotal page who detect this binary at the time of writing this blog.

Fig 8 - Cerber Ransomeware

Figure 8: Detection of extracted file from the installer in VirusTotal

Debugging the binary and extracting the configuration provides more insight into how Cerber works, including locations, AV vendors, and file extensions.

In our observation, Cerber doesn’t encrypt files for users in the following countries:

Armenia, Azerbaijan, Belarus, Georgia, Kyrgyzstan, Kazakhstan, Republic of Moldova, Russian Federation, Turkmenistan, Tajikistan, Ukraine and Uzbekistan

“Blacklist”:{“countries”:[“am”,”az”,”by”,”ge”,”kg”,”kz”,”md”,”ru”,”tm”,”tj”,”ua”,”uz”]

It also tries to stop working if it detects the following anti-virus solutions in place:

“av_blacklist”:[“kaspersky lab”,”avast software”,”eset”,”bitdefender”,”bitdefender agent”,”lavasoft”,”arcabit”,”arcavir”,”bullguard ltd”,”bullguard software”,”emsisoft anti-malware”,”escan”,”etrust ez armor”,”ca”,”f-secure”,”g data”,”trustport”]”

Finally, it encrypts files with the following 444 extensions that are likely to be associated with high-value business files:

“Encrypt”:{“files”:[[“.contact”, “.dbx”, “.doc”, “.docx”, “.jnt”, “.jpg”, “.mapimail”, “.msg”, “.oab”, “.ods”, “.pdf”, “.pps”, “.ppsm”, “.ppt”, “.pptm”, “.prf”, “.pst”, “.rar”, “.rtf”, “.txt”, “.wab”, “.xls”, “.xlsx”, “.xml”, “.zip”, “.1cd”, “.3ds”, “.3g2”, “.3gp”, “.7z”, “.7zip”, “.accdb”, “.aoi”, “.asf”, “.asp”, “.aspx”, “.asx”, “.avi”, “.bak”, “.cer”, “.cfg”, “.class”, “.config”, “.css”, “.csv”, “.db”, “.dds”, “.dwg”, “.dxf”, “.flf”, “.flv”, “.html”, “.idx”, “.js”, “.key”, “.kwm”, “.laccdb”, “.ldf”, “.lit”, “.m3u”, “.mbx”, “.md”, “.mdf”, “.mid”, “.mlb”, “.mov”, “.mp3”, “.mp4”, “.mpg”, “.obj”, “.odt”, “.pages”, “.php”, “.psd”, “.pwm”, “.rm”, “.safe”, “.sav”, “.save”, “.sql”, “.srt”, “.swf”, “.thm”, “.vob”, “.wav”, “.wma”, “.wmv”, “.xlsb”, “.3dm”, “.aac”, “.ai”, “.arw”, “.c”, “.cdr”, “.cls”, “.cpi”, “.cpp”, “.cs”, “.db3”, “.docm”, “.dot”, “.dotm”, “.dotx”, “.drw”, “.dxb”, “.eps”, “.fla”, “.flac”, “.fxg”, “.java”, “.m”, “.m4v”, “.max”, “.mdb”, “.pcd”, “.pct”, “.pl”, “.potm”, “.potx”, “.ppam”, “.ppsm”, “.ppsx”, “.pptm”, “.ps”, “.pspimage”, “.r3d”, “.rw2”, “.sldm”, “.sldx”, “.svg”, “.tga”, “.wps”, “.xla”, “.xlam”, “.xlm”, “.xlr”, “.xlsm”, “.xlt”, “.xltm”, “.xltx”, “.xlw”, “.act”, “.adp”, “.al”, “.bkp”, “.blend”, “.cdf”, “.cdx”, “.cgm”, “.cr2”, “.crt”, “.dac”, “.dbf”, “.dcr”, “.ddd”, “.design”, “.dtd”, “.fdb”, “.fff”, “.fpx”, “.h”, “.iif”, “.indd”, “.jpeg”, “.mos”, “.nd”, “.nsd”, “.nsf”, “.nsg”, “.nsh”, “.odc”, “.odp”, “.oil”, “.pas”, “.pat”, “.pef”, “.pfx”, “.ptx”, “.qbb”, “.qbm”, “.sas7bdat”, “.say”, “.st4”, “.st6”, “.stc”, “.sxc”, “.sxw”, “.tlg”, “.wad”, “.xlk”, “.aiff”, “.bin”, “.bmp”, “.cmt”, “.dat”, “.dit”, “.edb”, “.flvv”, “.gif”, “.groups”, “.hdd”, “.hpp”, “.log”, “.m2ts”, “.m4p”, “.mkv”, “.mpeg”, “.ndf”, “.nvram”, “.ogg”, “.ost”, “.pab”, “.pdb”, “.pif”, “.png”, “.qed”, “.qcow”, “.qcow2”, “.rvt”, “.st7”, “.stm”, “.vbox”, “.vdi”, “.vhd”, “.vhdx”, “.vmdk”, “.vmsd”, “.vmx”, “.vmxf”, “.3fr”, “.3pr”, “.ab4”, “.accde”, “.accdr”, “.accdt”, “.ach”, “.acr”, “.adb”, “.ads”, “.agdl”, “.ait”, “.apj”, “.asm”, “.awg”, “.back”, “.backup”, “.backupdb”, “.bank”, “.bay”, “.bdb”, “.bgt”, “.bik”, “.bpw”, “.cdr3”, “.cdr4”, “.cdr5”, “.cdr6”, “.cdrw”, “.ce1”, “.ce2”, “.cib”, “.craw”, “.crw”, “.csh”, “.csl”, “.db_journal”, “.dc2”, “.dcs”, “.ddoc”, “.ddrw”, “.der”, “.des”, “.dgc”, “.djvu”, “.dng”, “.drf”, “.dxg”, “.eml”, “.erbsql”, “.erf”, “.exf”, “.ffd”, “.fh”, “.fhd”, “.gray”, “.grey”, “.gry”, “.hbk”, “.ibank”, “.ibd”, “.ibz”, “.iiq”, “.incpas”, “.jpe”, “.kc2”, “.kdbx”, “.kdc”, “.kpdx”, “.lua”, “.mdc”, “.mef”, “.mfw”, “.mmw”, “.mny”, “.moneywell”, “.mrw”, “.myd”, “.ndd”, “.nef”, “.nk2”, “.nop”, “.nrw”, “.ns2”, “.ns3”, “.ns4”, “.nwb”, “.nx2”, “.nxl”, “.nyf”, “.odb”, “.odf”, “.odg”, “.odm”, “.orf”, “.otg”, “.oth”, “.otp”, “.ots”, “.ott”, “.p12”, “.p7b”, “.p7c”, “.pdd”, “.pem”, “.plus_muhd”, “.plc”, “.pot”, “.pptx”, “.psafe3”, “.py”, “.qba”, “.qbr”, “.qbw”, “.qbx”, “.qby”, “.raf”, “.rat”, “.raw”, “.rdb”, “.rwl”, “.rwz”, “.s3db”, “.sd0”, “.sda”, “.sdf”, “.sqlite”, “.sqlite3”, “.sqlitedb”, “.sr2”, “.srf”, “.srw”, “.st5”, “.st8”, “.std”, “.sti”, “.stw”, “.stx”, “.sxd”, “.sxg”, “.sxi”, “.sxm”, “.tex”, “.wallet”, “.wb2”, “.wpd”, “.x11”, “.x3f”, “.xis”, “.ycbcra”, “.yuv”, “.mab”, “.json”, “.ini”, “.sdb”, “.sqlite-shm”, “.sqlite-wal”, “.msf”, “.jar”, “.cdb”, “.srb”, “.abd”, “.qtb”, “.cfn”, “.info”, “.info_”, “.flb”, “.def”, “.atb”, “.tbn”, “.tbb”, “.tlx”, “.pml”, “.pmo”, “.pnx”, “.pnc”, “.pmi”, “.pmm”, “.lck”, “.pm!”, “.pmr”, “.usr”, “.pnd”, “.pmj”, “.pm”, “.lock”, “.srs”, “.pbf”, “.omg”, “.wmf”, “.sh”, “.war”, “.ascx”, “.tif”, “.k2p”, “.apk”, “.asset”, “.bsa”, “.d3dbsp”, “.das”, “.forge”, “.