BRUSHFIRE
MITRE ATT&CK: S9011 View on attack.mitre.org
Aliases: BRUSHFIRE
- First seen
- 2025-03-01 00:00:00
- Malware type
- backdoor
- Family
- Malware family
- Operating systems
- linux, network-devices
- Profile updated
- 2026-07-07 14:30:11
Targeted industries: government-and-public-sector technology-and-telecommunications energy-and-utilities
Targeted regions: country_code:cn country_code:us
Context
BRUSHFIRE is a passive backdoor written in C that executes in-memory within an existing process. First reported in March 2025, BRUSHFIRE has been observed in activity attributed to People's Republic of China (PRC) state-affiliated threat actors, including UNC5221 and SYLVANITE.
Detection coverage
- 17 Sigma rules
Malware & tools used
- Deobfuscate/Decode Files or Information (attack-pattern)
- Exfiltration Over Asymmetric Encrypted Non-C2 Protocol (attack-pattern)
- Traffic Signaling (attack-pattern)
- Reflective Code Loading (attack-pattern)
Exploited vulnerabilities
- CVE-2025-22457 (vulnerability)
Reports & references
- cloud.google.com — China Nexus Exploiting Critical Ivanti Vulnerability (report)
- MITRE ATT&CK — S9011 (report)
- hub.dragos.com — 2026 Yir Executivebriefing%20O G (report)
- picussecurity.com — Unc5221 Cve 2025 22457 Ivanti Connect Secure (report)