Attributed metadata history

Financially Motivated Threat Actor BREEZE COMET Targets Brazil

Introduction  Beginning in 2024 Mandiant investigated a string of compromises affecting Brazilian financial services, retail, and eCommerce organizations. Google Threat Intelligence Group (GTIG) tracks this activity as BREEZE COMET (formerly UNC5669), a financially motivated threat actor specializing in manipulating payment systems and banking software in Brazil to conduct fraudulent transfers. This activity overlaps with operations publicly reported as Plump Spider and SHADOW-AETHER-064. In this blog, we detail BREEZE COMET’s tactics and toolkit, and provide mitigation recommendations and detections to support organizations in defending against this active and developing threat. BREEZE COMET tactics have evolved over time to leverage a customized malware suite and compromised, trusted websites to facilitate initial access, command and control (C2), and to interact with financial software and payment APIs. BREEZE COMET’s operational infrastructure may also indicate intent to expand their infrastructure footprint to other countries in Latin America and Africa. Additionally, we have evidence that BREEZE COMET is using generative artificial intelligence (AI) to support malware development, which may further increase the scale, speed, and sophistication of their operations in the future.   BREEZE COMET Targets Brazilian Financial Technology  BREEZE COMET operations target organizations with permission to conduct transactions through banking software, APIs, and payment systems such as Pix, STR, and Boleto. This typically includes banks, payment processors, retailers, exchanges, as well as fintech and banking software providers.  To achieve their objective of conducting fraudulent transfers, BREEZE COMET must maintain: Access to the National Financial System Network (Rede Nacional do Setor Financeiro, RSFN) through an entity with this access. Access to mTLS credentials that allow sending authenticated payloads with transactional orders to Pix, STR (Brazilian Reserves Transfer System), or any transactional listener to be executed with minimal restrictions in the name of an organization with available funds. Persistent access to multiple accounts in targeted organizations’ Active Directory and/or cloud environments. Understanding of an organization’s transfer processing procedures, network controls, fintech integrations and anti-fraud systems. In order to support these requirements, BREEZE COMET evolved to operate in multiple compromised environments at the same time, crafting custom C2 malware to automate activities such as reconnaissance, lateral movement, persistence, and exfiltration.  Initial Compromise and Establish Foothold BREEZE COMET has used various methods for initial access. In early compromises, Mandiant observed this threat actor use password spraying as well as voice calls impersonating IT support teams to convince users to install Remote Monitoring and Management (RMM) tools such as AnyDesk. Axur corroborates use of voice phishing, and suggests that the group has also attempted to recruit insiders at targeted organizations. In mid-2025, GTIG observed BREEZE COMET using compromised Brazilian small government websites to stage RMM tools, infostealers disguised as legitimate tax or receipt documents (e.g., ComprovantePDF.exe), or backdoors such as XWORM set to persist via automated startup shortcut modifications. XWORM is a backdoor that is widely available for purchase on cyber crime forums, with leaked or “cracked” versions also available. BREEZE COMET then used these compromised government websites to facilitate social engineering operations for initial access, and as C2 endpoints. The use of compromised, trusted infrastructure allowed the threat actors to avoid detection by network domain reputation filters. GTIG also observed BREEZE COMET replicating this behavior with municipal domains in Nigeria, Paraguay, Ghana, and Venezuela, suggesting a potentially growing targeting focus. Analysis

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