• Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
MUST READ

Arizona woman sentenced for aiding North Korea in U.S. IT job fraud scheme

 | 

Operation CargoTalon targets Russia’s aerospace with EAGLET malware,

 | 

Unpatched flaw in EoL LG LNV5110R cameras lets hackers gain Admin access

 | 

Koske, a new AI-Generated Linux malware appears in the threat landscape

 | 

Mitel patches critical MiVoice MX-ONE Auth bypass flaw

 | 

Coyote malware is first-ever malware abusing Windows UI Automation

 | 

SonicWall fixed critical flaw in SMA 100 devices exploited in Overstep malware attacks

 | 

DSPM & AI Are Booming: $17.87B and $4.8T Markets by 2033

 | 

Stealth backdoor found in WordPress mu-Plugins folder

 | 

U.S. CISA adds CrushFTP, Google Chromium, and SysAid flaws to its Known Exploited Vulnerabilities catalog

 | 

U.S. CISA urges FCEB agencies to fix two Microsoft SharePoint flaws immediately and added them to its Known Exploited Vulnerabilities catalog

 | 

Sophos fixed two critical Sophos Firewall vulnerabilities

 | 

French Authorities confirm XSS.is admin arrested in Ukraine

 | 

Microsoft linked attacks on SharePoint flaws to China-nexus actors

 | 

Cisco confirms active exploitation of ISE and ISE-PIC flaws

 | 

SharePoint under fire: new ToolShell attacks target enterprises

 | 

CrushFTP zero-day actively exploited at least since July 18

 | 

Hardcoded credentials found in HPE Aruba Instant On Wi-Fi devices

 | 

MuddyWater deploys new DCHSpy variants amid Iran-Israel conflict

 | 

U.S. CISA urges to immediately patch Microsoft SharePoint flaw adding it to its Known Exploited Vulnerabilities catalog

 | 
  • Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
  • Home
  • Breaking News
  • Malware
  • UNC2565 threat actors continue to improve the GOOTLOADER malware

UNC2565 threat actors continue to improve the GOOTLOADER malware

Pierluigi Paganini January 30, 2023

The threat actors behind the GOOTLOADER malware continues to improve their code by adding new components and implementing new obfuscation techniques.

Mandiant researchers reported that the UNC2565 group behind the GOOTLOADER malware (aka Gootkit) continues to improve their code by adding new components and implementing new obfuscation techniques.

Gootkit runs on an access-a-as-a-service model, it is used by different groups to drop additional malicious payloads on the compromised systems. Gootkit has been known to use fileless techniques to deliver threats such as the SunCrypt, and REvil (Sodinokibi) ransomware, Kronos trojans, and Cobalt Strike.

In the past, Gootkit distributed malware masquerading as freeware installers and it used legal documents to trick users into downloading these files. 

The attack chain starts with a user searching for specific information in a search engine. Attackers use black SEO technique to display a website compromised by Gootkit operators among the results.

Upon visiting the website, the victim will notice that it is presented as an online forum directly answering his query. This forum hosted a ZIP archive that contains the malicious .js file, which is used to establish persistence and drop a Cobalt Strike binary in the memory of the infected system.

In November 2022, Mandiant researchers spotted a new variant of GOOTLOADER, tracked as GOOTLOADER.POWERSHELL, that used a new infection chain. The new variant writes a second .JS file to disk and creates a scheduled task to execute it. Below is the attack chain of this new variant:

  1. The user visits an UNC2565-compromised site (usually related to business documents) and downloads a malicious ZIP archive.
  2. The malicious ZIP file is saved to the user’s Downloads folder.
  3. The user opens the ZIP file and clicks the .JS file inside. This is a trojanized JavaScript library containing an obfuscated JScript file, which will ultimately execute GOOTLOADER.POWERSHELL. Recently observed trojanized JavaScript libraries include jQuery, Chroma.js, and Underscore.js.
  4. The JS file is launched using WScript.exe.
  5. The WScript.exe process creates an inflated file with a .LOG extension to C:\Users\%USERNAME%\AppData\Roaming\<RANDOM_DIRECTORY>\<HARD_CODED_FILE_NAME>. The dropper writes more obfuscated JScript code followed by a padding of random characters to increase the file size.
  6. The .LOG file is renamed with a .JS file extension.
  7. The dropper creates a scheduled task that executes the new JScript file. The scheduled task is executed immediately after creation but also serves as a persistence mechanism to run the second JScript file at the next logon.
  8. WScript.exe and CScript.exe launch a PowerShell process that reaches out to 10 hard coded domains.
    • Victim information collected includes environment variables, Windows OS version, filenames, and running processes. This information is Gzip compressed, Base64 encoded, and sent to the command and control (C2) server in the Cookie header.
  9. The C2 returns a payload, which is executed using the Invoke-Expression PowerShell cmdlet. This leads to the download of two payloads into registry keys: FONELAUNCH and a secondary payload to be executed by FONELAUNCH (mirroring steps 6 through 10 of the previous infection chain).
GOOTLOADER

Mandiant researchers observed the UNC2565 group adopting three obfuscation techniques, such as hiding the code within altered versions of legitimate JavaScript libraries such as jQuery, Chroma.js, and Underscore.js, in an attempt to evade detection.

  Variant 1Variant 2Variant 3
First ObservedFeb 2021Oct 2021Nov 2022
Malicious CodeOne obfuscated block of code, easily recognizable.Malicious code has been nested within the file. Early samples had all the variables in one block of code, later samples spread the code throughout the file.Malicious code has been nested throughout the file. Additional string variables added for the second deobfuscation iteration.
Payload (See Infection Chain)GOOTLOADERGOOTLOADERGOOTLOADER.POWERSHELL 

“Beginning in November 2022, Managed Defense observed a new obfuscation variant, tracked as variant 3, with modified infection that is more complex than the previous variants. This new variant contains additional string variables that are used in a second deobfuscation stage.” reads the report published by Mandiant. “This new variant has been observed trojanizing several legitimate JavaScript libraries, including jQuery, Chroma.js, and Underscore.js”

Upon successful execution of the GOOTLOADER file, additional payloads are downloaded, including FONELAUNCH and Cobalt Strike BEACON or SNOWCONE that will be stored in the registry. Then the payloads are executed via PowerShell in the later stages.

FONELAUNCH is a .NET-based launcher, it loads an encoded payload from the registry into memory. Since May 2021, the researchers have observed threat actors using three different variants of FONELAUNCH that differ in their loading mechanism:

  • FONELAUNCH.FAX reads and decodes data from the HKCU\SOFTWARE\Microsoft\Fax\%USERNAME% registry key. The returned content is expected to be a .NET assembly, which is loaded at runtime into memory.
  • FONELAUNCH.PHONE mainly reads and decodes data placed in a specific registry key. The returned data is expected to be a DLL, which is loaded via a publicly available DynamicDllLoader project.
  • FONELAUNCH.DIALTONE reads and decodes data from the HKCU\SOFTWARE\Microsoft\%USERNAME% registry key. The returned content is expected to be a PE file, which is injected into a separate process and executed.

The report published by Mandiant also includes Indicators of Compromise (IoCs) and YARA rules associated with these threats.

Follow me on Twitter: @securityaffairs and Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, GOOTLOADER)


facebook linkedin twitter

Cybercrime gootloader hacking news information security news IT Information Security malware Pierluigi Paganini Security Affairs Security News UNC2565

you might also like

Pierluigi Paganini July 26, 2025
Arizona woman sentenced for aiding North Korea in U.S. IT job fraud scheme
Read more
Pierluigi Paganini July 25, 2025
Operation CargoTalon targets Russia’s aerospace with EAGLET malware,
Read more

leave a comment

newsletter

Subscribe to my email list and stay
up-to-date!

    recent articles

    Arizona woman sentenced for aiding North Korea in U.S. IT job fraud scheme

    Intelligence / July 26, 2025

    Operation CargoTalon targets Russia’s aerospace with EAGLET malware,

    Intelligence / July 25, 2025

    Unpatched flaw in EoL LG LNV5110R cameras lets hackers gain Admin access

    Security / July 25, 2025

    Koske, a new AI-Generated Linux malware appears in the threat landscape

    Malware / July 25, 2025

    Mitel patches critical MiVoice MX-ONE Auth bypass flaw

    Security / July 25, 2025

    To contact me write an email to:

    Pierluigi Paganini :
    pierluigi.paganini@securityaffairs.co

    LEARN MORE

    QUICK LINKS

    • Home
    • Cyber Crime
    • Cyber warfare
    • APT
    • Data Breach
    • Deep Web
    • Digital ID
    • Hacking
    • Hacktivism
    • Intelligence
    • Internet of Things
    • Laws and regulations
    • Malware
    • Mobile
    • Reports
    • Security
    • Social Networks
    • Terrorism
    • ICS-SCADA
    • POLICIES
    • Contact me

    Copyright@securityaffairs 2024

    We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept All”, you consent to the use of ALL the cookies. However, you may visit "Cookie Settings" to provide a controlled consent.
    Cookie SettingsAccept All
    Manage consent

    Privacy Overview

    This website uses cookies to improve your experience while you navigate through the website. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities...
    Necessary
    Always Enabled
    Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
    Non-necessary
    Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
    SAVE & ACCEPT