• 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

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

 | 

Microsoft issues emergency patches for SharePoint zero-days exploited in "ToolShell" attacks

 | 

SharePoint zero-day CVE-2025-53770 actively exploited in the wild

 | 

Singapore warns China-linked group UNC3886 targets its critical infrastructure

 | 

U.S. CISA adds Fortinet FortiWeb flaw to its Known Exploited Vulnerabilities catalog

 | 

SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 54

 | 
  • 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
  • APT
  • Breaking News
  • Hacking
  • Intelligence
  • Malware
  • Security
  • China-linked APT41 used Google Calendar as C2 to control its TOUGHPROGRESS malware

China-linked APT41 used Google Calendar as C2 to control its TOUGHPROGRESS malware

Pierluigi Paganini May 29, 2025

Google says China-linked group APT41 controlled malware via Google Calendar to target governments through a hacked site.

Google warns that China-linked APT41 used TOUGHPROGRESS malware with Google Calendar as C2, targeting various government entities via a compromised website.

” In late October 2024, GTIG discovered an exploited government website hosting malware being used to target multiple other government entities. The exploited site delivered a malware payload, which we have dubbed “TOUGHPROGRESS”, that took advantage of Google Calendar for command and control (C2).” reads the report published by Google. “Misuse of cloud services for C2 is a technique that many threat actors leverage in order to blend in with legitimate activity.”

APT41 used spear phishing emails with a ZIP file hosted on a hacked government site. The ZIP pretended to be a document about export declarations and included a disguised LNK file and images of arthropods. Two of the images were fake, one of them contained an encrypted payload, the other a DLL used to decrypt and launch the malicious code when the victim clicked the link. A decoy PDF was shown to avoid suspicion.

The malware operates in three stealthy stages, each with a specific role and advanced evasion tactics. The first stage PLUSDROP decrypts and runs the next stage entirely in memory. Then, the second stage PLUSINJECT uses process hollowing to inject malicious code into a legitimate Windows process like svchost.exe. Finally, TOUGHPROGRESS carries out the attacker’s tasks on the infected system, communicating with its operators through Google Calendar to avoid detection.

TOUGHPROGRESS starts by decrypting embedded shellcode using a hardcoded XOR key, then decompresses a DLL in memory with LZNT1. This DLL uses advanced control flow obfuscation techniques, like register-based indirect calls, dynamic address arithmetic, 64-bit register overflow, and function dispatch tables, to hide its behavior. These tricks make it hard for analysis tools to trace how the malware operates, significantly complicating reverse engineering.

TOUGHPROGRESS uses Google Calendar as a stealthy command-and-control (C2) channel. It creates hidden events on specific hardcoded dates to exfiltrate stolen data and receive commands. The malware encrypts both data and commands using XOR keys and compresses messages with LZNT1. Commands are placed in Calendar event descriptions, retrieved and decrypted by the malware, then executed on the infected system. Results are encrypted and uploaded back as new calendar events, effectively turning Calendar into a covert communication tool.

APT41 TOUGHPROGRESS
APT41 TOUGHPROGRESS

“To disrupt APT41 and TOUGHPROGRESS malware, we have developed custom fingerprints to identify and take down attacker-controlled Calendars.” continues the report. “We have also terminated attacker-controlled Workspace projects, effectively dismantling the infrastructure that APT41 relied on for this campaign. Additionally, we updated file detections and added malicious domains and URLs to the Google Safe Browsing blocklist. “

Google GTIG and Mandiant Consulting alerted affected organizations, sharing TOUGHPROGRESS network logs and threat intel to support detection and response efforts.

Follow me on Twitter: @securityaffairs and Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, APT41)


facebook linkedin twitter

APT41 Google Calendar Hacking hacking news information security news IT Information Security malware Pierluigi Paganini Security Affairs Security News TOUGHPROGRESS

you might also like

Pierluigi Paganini July 24, 2025
Coyote malware is first-ever malware abusing Windows UI Automation
Read more
Pierluigi Paganini July 24, 2025
SonicWall fixed critical flaw in SMA 100 devices exploited in Overstep malware attacks
Read more

leave a comment

newsletter

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

    recent articles

    Coyote malware is first-ever malware abusing Windows UI Automation

    Malware / July 24, 2025

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

    Security / July 24, 2025

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

    Security / July 24, 2025

    Stealth backdoor found in WordPress mu-Plugins folder

    Malware / July 24, 2025

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

    Hacking / July 24, 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