---
type: "attack-path"
title: "FRUMPYTOAD-TOUGHPROGRESS-2025"
description: "FrumpyToad (APT41/Wicked Panda/Brass Typhoon) TOUGHPROGRESS campaign, October 2024 through mid-2025."
resource: "tlctc:attack-path:frumpytoad-toughprogress-2025"
tags:
  - "attack-path"
  - "cluster-9"
  - "cluster-7"
  - "cluster-1"
  - "confidence-high"
timestamp: "2026-04-09T00:00:00Z"
tlctc_version: "2.3"
---
# FRUMPYTOAD-TOUGHPROGRESS-2025

## Attack path

```
||[email][@FrumpyToad→@Victim]|| #9 →[Δt=~1h] #7 (FEC) →[Δt=instant] #1 + [DRE: C]
```

# Schema

| Step | Cluster | Boundary | Δt→next | DRE |
|---|---|---|---|---|
| s1-spearphishing-delivery | [#9](/clusters/cluster-9.md) | \|\|[email][@FrumpyToad→@Victim]\|\| | ~1h |  |
| s2-toughprogress-execution | [#7](/clusters/cluster-7.md) (FEC) |  | instant |  |
| s3-google-calendar-c2 | [#1](/clusters/cluster-1.md) |  |  | C |

## Step notes

- **s1-spearphishing-delivery:** Spear-phishing emails targeting global financial sector and SaaS providers. Emails redirect through a chain of serverless platforms (legitimate cloud services abused for redirection) to host malicious ZIP archives on compromised government websites. The human boundary crossing is the #9 step — the victim must open the email and follow the redirect chain. The serverless platforms serve as transit infrastructure for delivery.
- **s2-toughprogress-execution:** Victim opens the malicious ZIP archive, executing the TOUGHPROGRESS malware. R-EXEC: foreign executable content executes on the victim's system — recorded as #7 with fec_executed: true. TOUGHPROGRESS is a custom malware family designed for cloud-to-cloud C2 operations.
- **s3-google-calendar-c2:** TOUGHPROGRESS establishes a cloud-to-cloud C2 loop using Google Calendar. The malware reads encrypted commands from calendar events dated July 30-31, 2023, and writes exfiltrated data to event descriptions dated May 30, 2023 (hardcoded). All traffic remains within Google's encrypted ecosystem — the actor communicates with infected hosts without ever connecting to a malicious domain. This is #1 Abuse of Functions: Google Calendar's read/write API operates exactly as designed. The event description field is used within its intended parameters. Detection indicator: unusual volume of API calls to Google Calendar from non-interactive processes. DRE: C — exfiltrated data embedded in calendar events. The LotX (Living off the XaaS) approach makes this nearly invisible to standard perimeter defenses.

# Citations

FrumpyToad (APT41/Wicked Panda/Brass Typhoon) TOUGHPROGRESS campaign, October 2024 through mid-2025. Tracked by Cloudforce One. A sophisticated cloud-to-cloud C2 loop weaponizing Google Calendar to blend into legitimate enterprise traffic. Spear-phishing emails redirected through a chain of serverless platforms to host malicious ZIP archives on compromised government sites. The TOUGHPROGRESS malware reads and writes encrypted commands directly into Google Calendar event descriptions — stolen data is embedded in events dated May 30, 2023 (hardcoded); operators place commands in events dated July 30-31, 2023 (polled and executed). This Living off the XaaS (LotX) technique allows the actor to communicate with infected hosts without ever connecting to a malicious domain. Attack path: #9 ||[email][@External->@Org]|| -> #7 -> #1 + [DRE: C]. Sources: Cloudflare 2026 Threat Report (pp. 23), Cloudforce One telemetry.
