• Skip to primary navigation
  • Skip to main content
  • Skip to footer

Cisco Umbrella

Enterprise network security

  • Contact Sales
  • Login
    • Umbrella Login
    • Cloudlock Login
  • Why Us
    • Why Cisco Umbrella
      • Why Try Umbrella
      • Why DNS Security
      • Why Umbrella SASE
      • Our Customers
      • Customer Stories
      • Why Cisco Secure
    • Fast Reliable Cloud
      • Global Cloud Architecture
      • Cloud Network Status
      • Global Cloud Network Activity
    • Unmatched Intelligence
      • A New Approach to Cybersecurity
      • Interactive Intelligence
      • Cyber Attack Prevention
      • Umbrella and Cisco Talos Threat Intelligence
    • Extensive Integrations
      • IT Security Integrations
      • Hardware Integrations
      • Meraki Integration
      • Cisco Umbrella and SecureX
  • Products
    • Cisco Umbrella Products
      • Cisco Umbrella Cloud Security Service
      • Recursive DNS Services
      • Cisco Umbrella SIG
      • Umbrella Investigate
      • What’s New
    • Product Packages
      • Cisco Umbrella Package Comparison
      • – DNS Security Essentials Package
      • – DNS Security Advantage Package
      • – SIG Essentials Package
      • – SIG Advantage Package
      • Umbrella Support Packages
    • Functionality
      • DNS-Layer Security
      • Secure Web Gateway
      • Cloud Access Security Broker (CASB)
      • Cloud Data Loss Prevention (DLP)
      • Cloud-Delivered Firewall
      • Cloud Malware Protection
      • Remote Browser Isolation (RBI)
    • Man on a laptop with headphones on. He is attending a Cisco Umbrella Live Demo
  • Solutions
    • SASE & SSE Solutions
      • Cisco Umbrella SASE
      • Secure Access Service Edge (SASE)
      • What is SASE
      • What is Security Service Edge (SSE)
    • Functionality Solutions
      • Web Content Filtering
      • Secure Direct Internet Access
      • Shadow IT Discovery & App Blocking
      • Fast Incident Response
      • Unified Threat Management
      • Protect Mobile Users
      • Securing Remote and Roaming Users
    • Network Solutions
      • Guest Wi-Fi Security
      • SD-WAN Security
      • Off-Network Endpoint Security
    • Industry Solutions
      • Government and Public Sector Cybersecurity
      • Financial Services Security
      • Cybersecurity for Manufacturing
      • Higher Education Security
      • K-12 Schools Security
      • Healthcare, Retail and Hospitality Security
      • Enterprise Cloud Security
      • Small Business Cybersecurity
  • Resources
    • Content Library
      • Top Resources
      • Cybersecurity Webinars
      • Events
      • Research Reports
      • Case Studies
      • Videos
      • Datasheets
      • eBooks
      • Solution Briefs
    • International Documents
      • Deutsch/German
      • Español/Spanish
      • Français/French
      • Italiano/Italian
      • 日本語/Japanese
    • Security Definitions
      • What is Secure Access Service Edge (SASE)
      • What is Security Service Edge (SSE)
      • What is a Cloud Access Security Broker (CASB)
      • Cyber Threat Categories and Definitions
    • For Customers
      • Support
      • Customer Success Webinars
      • Cisco Umbrella Studio
  • Trends & Threats
    • Market Trends
      • Hybrid Workforce
      • Rise of Remote Workers
      • Secure Internet Gateway (SIG)
    • Security Threats
      • How to Stop Phishing Attacks
      • Malware Detection and Protection
      • Ransomware is on the Rise
      • Cryptomining Malware Protection
      • Cybersecurity Threat Landscape
      • Global Cyber Threat Intelligence
    •  
    • Woman connecting confidently to any device anywhere
  • Partners
    • Channel Partners
      • Partner Program
      • Become a Partner
    • Service Providers
      • Secure Connectivity
      • Managed Security for MSSPs
      • Managed IT for MSPs
    •  
    • Person looking down at laptop. They are connecting and working securely
  • Blog
    • News & Product Posts
      • Latest Posts
      • Products & Services
      • Customer Focus
      • Feature Spotlight
    • Cybersecurity Posts
      • Security
      • Threats
      • Cybersecurity Threat Spotlight
      • Research
    •  
    • Register for a webinar - with illustration of connecting securely to the cloud
  • Contact Us
  • Umbrella Login
  • Cloudlock Login
  • Free Trial
Threats

WildFire Ransomware Catching On

Author avatar of Brad AntoniewiczBrad Antoniewicz
Updated — July 24, 2020 • 4 minute read
View blog >

WildFire Ransomware Domains
WildFire Ransomware Domains

Sometimes people naively open .onion links in their browsers, so every few days I’ll check out what pops up in Investigate to dig in a little deeper. Today I came across gsxrmcgsygcxfkbb.onion and poof! down the rabbit hole I tumbled.

Kelihos Aids Distribution

We first started seeing WildFire ransomware hitting our resolvers on June 21, 2016, and there has been an increase in activity over the last few days. This is most likely due to a bump in distribution by the Kelihos Botnet.
Before the ransomware takes hold, systems infected with WildFire will aggressively attempt to communicate exithub1.su, exithub2.su, exithub-pql.su and exithub-xuq.su. If we look at the number of requests for those domains, we see a nice influx:
Influx of activity associated with WildFire domains
Most infection reports are coming in from the Netherlands. If we check out who is requesting these domains, we see that most requests originate from the same place: 95% Netherlands.
WildFire activity in NL

Word Macro via Email

Malicious MacroThe journey starts with an all-too-common initial infection vector: a user receives an email with a macro-embedded Word document attached. In this case, it was titled BT-32084.doc (8f8741e18aa6b7b8282402f0aea5e0c9). 
The Word document displays a message to the reader instructing them to enable macros to view the content. Those with an eye for detail might notice that the document is 205 pages long! This is because it’s using an oldie-but-goodie trick by embedding its payload in the document text, rather than within a document stream. At first glance, you might miss it since all of the pages appear to be blank. An easy way to view this hidden “treat” is to select all text in the document with CTRL+A, then change the color to something other than white, like red. Here’s what you’ll see:
Clever
The prevalence of 0x33 bytes suggests that the payload could be XOR’ed with 0x33. Rather than take this avenue for analysis, let’s use another technique to take the express train to the binary.

Payload Extraction

oledump will allow you to dump the various streams of the document, or if you’re in a tight analysis environment and speed is more important than thoroughness, you could just ‘ride-or-die’ and execute the macro. I have always thought DMX and Fetty were onto something, so let’s go for ‘ride-or-die’.
Searching for calls to the Shell() function within the macro will fast-track you to what is being executed. If we set a breakpoint on the call and inspect its parameters at runtime, we can see that the macro is calling C:\ProgramData\Memsys\ms.exe (f157038d7b105cee1b8bb8c957f1ec39), which means it likely wrote ms.exe to the file system earlier in macro. 
nice function name

Self-Extracting Archive

With ms.exe resting nice and comfortably on your file system, you might be so inclined to open it up in IDA to let the real work begin.
SFX
That is, until a few strings indicating this is a self-extracting archive bring you right back to “ride-or-die”.
The good stuffExecuting ms.exe, checking %TEMP%\RarSFX or extracting with 7zip will yield three files: Bigrmkwhrr.png (645e7f63886d74c5edd149caac1b41cd), Imvenagxehdoj.xml (9f543d1ca1fe9a2ea69984f2a3804fe1), and Jnmsiyyks.exe (a86f56fee647446d33d555b25d871bf8). 

Dot Net Obfuscation!

WildFire’s second-stage executable (Jnmsiyyks.exe ) is just really a wrapper around the supplemental files that were extracted in the same directory. The obfuscated code creates a big nasty AppContext with the contents of Bigrmkwhrr.png as a variable, decodes it, and then launches it as a form in a thread.

Dot Net Ransomware

Luckily, this thread’s assembly is not obfuscated, so with some quick XOR’ing, we have access to the full source of the source. Here’s a quick script to handle the XOR’ing:

Network Activity

As mentioned above, the malware aggressively attempts to contact its servers — exithub1.su, exithub2.su, exithub-pql.su and exithub-xuq.su. Once it is successful, it will POST base64-encoded data to the server. I changed the output slightly to anonymize it:
{"action":"connect","uid":"abcdef0123","rid":"email_spread_XXX","username":"user","computername":"LAPTOP","ip":"123.45.67.89","country":"UE"}
If the registration is successful, the server will return a password:
{“status”:”success”,”password”:”sAKFSdgVKVdFLfvjwWkvdjjXXlotynss”}
and the client will update the server with its status in increments:
{"action":"update","uid":"abcdef0123","filecount":"8320"}
Then, upon success, the server will return:
{"status":"success","null":"null"}

Notification and Payment

Once WildFire encrypts all of the files on the system, the ransomware lets the user know by the now-ominous ransomware notification page. One interesting thing here is that the payment page is hosted on both the internet and on Tor. Usually bad actors only leverage Tor to remain anonymous, but here the attacker is either confident in the privacy of the system hosting the landing page, or doesn’t care to remain anonymous.
Notification and payment

Attribution

Directory Listings and JSI’m half-joking about the heading of this section, we all know attribution is hard. But if we wanted to comment slightly on the topic, we could imply from directory listings shown in the image to the right that this system may have been set up/compromised on June 20th. And, due to some friendly comments in the HTML source of the page shown below the directory listing, we see that the author needs to fix the timer javascript. You read Russian too, right?

Suggested Blogs

  • Cybersecurity Threat Spotlight: Emotet, RedLine Stealer, and Magnat Backdoor February 3, 2022 5 minute read
  • Using DNS-layer security to detect and prevent ransomware attacks August 12, 2021 6 minute read
  • The cost of ransomware attacks: Why and how you should protect your data August 10, 2021 4 minute read

Share this blog

FacebookTweetLinkedIn

Follow Us

  • Twitter
  • Facebook
  • LinkedIn
  • YouTube

Footer Sections

What we make

  • Cloud Security Service
  • DNS-Layer Network Security
  • Secure Web Gateway
  • Security Packages

Who we are

  • Global Cloud Architecture
  • Cloud Network Status
  • Cloud Network Activity
  • OpenDNS is now Umbrella
  • Cisco Umbrella Blog

Learn more

  • Webinars
  • Careers
  • Support
  • Cisco Umbrella Live Demo
  • Contact Sales
Umbrella by Cisco
208.67.222.222+208.67.220.220
2620:119:35::35+2620:119:53::53
Sign up for a Free Trial
  • Cisco Online Privacy Statement
  • Terms of Service
  • Sitemap

© 2023 Cisco Umbrella