Threat Intelligence
HEAVYGRAM Malware: Telegram C2 Triage Checklist
Use the FBI’s September 2026 HEAVYGRAM update to investigate suspicious installers, correlate Telegram traffic, and brief leadership on confirmed exposure.
Updated 2026-09-21 · 3 min read
Initial review
Installer provenance
Establish who supplied the software and whether execution followed an unsolicited support offer.
Detection
Correlated evidence
Connect network activity to the originating process, file evidence, and security-setting changes.
Leadership brief
Confirmed exposure
Separate observed collection or transfer from malware capabilities and unresolved evidence gaps.
Useful CyberPrism references
FBI HEAVYGRAM Malware Analysis
September 15, 2026 update with malware analysis, indicators, and detection signatures.
CyberPrism RIPD Framework
Explore the framework alongside your investigation and response planning.
Threat Actor Intelligence
Review actor context while keeping local incident findings tied to evidence.
What should teams do after a HEAVYGRAM alert?
Validate the alert against endpoint evidence, preserve the installation timeline, and contain confirmed malicious activity. Correlate Telegram connections with the process making them before deciding what the traffic means.
The FBI’s September 15, 2026 update analyzes HEAVYGRAM malware attributed to Iranian Ministry of Intelligence and Security actors targeting dissidents, journalists, and opposition groups. It adds indicators and detection signatures to an earlier March warning. [FBI HEAVYGRAM update](https://www.ic3.gov/CSA/2026/260915.pdf).
Trace the support offer and installer
The FBI describes unsolicited IT-service offers through social platforms, followed by remote-access requests or disguised installers. An analyzed sample posed as a Telegram authenticator. [FBI delivery analysis](https://www.ic3.gov/CSA/2026/260915.pdf).
Ask the affected user to preserve the original conversation, download link, and support instructions. Record the file hash, execution time, device, account, and any remote-access session; avoid reopening the installer during evidence collection.
Correlate indicators with endpoint behavior
The report documents attempts to add Microsoft Defender exclusions and malware communications with the Telegram API. These provide investigation leads beyond filenames. [FBI technical analysis](https://www.ic3.gov/CSA/2026/260915.pdf).
Suggested triage: search the published indicators across available endpoint records, then connect matches to process ancestry, security-setting changes, and outbound connections. Record the time range and devices searched so a negative result has a defined scope.
Contain access and investigate collection separately
Analyzed malware includes functions for collecting browser data and extracting Outlook messages and attachments. Capability alone does not establish that those functions ran on a particular device. [FBI capability analysis](https://www.ic3.gov/CSA/2026/260915.pdf).
For a confirmed infection, activate the incident-response process and isolate affected endpoints while preserving evidence. Have identity responders assess exposed accounts and sessions, using a trusted device for recovery actions.
Track collection and transfer as separate findings: what files were accessed or staged, what outbound activity was observed, and what logging gaps prevent a conclusion.
Give leadership a decision-ready update
For the September 21, 2026 review, report affected devices, containment status, observed data activity, and outstanding evidence gaps. Assign an owner and next update time to each unresolved item.
Keep attribution qualified: the FBI’s campaign assessment supplies context, while your incident findings must rest on local evidence. Close the review with specific changes to software installation approvals, remote-support verification, or detection coverage.
FAQ
Does Telegram traffic prove HEAVYGRAM infection?
No. A destination alone does not identify the software using it. Correlate the connection with endpoint indicators, the originating process, and surrounding activity before classifying it as malicious.
Where should defenders obtain HEAVYGRAM indicators?
Use the indicators and detection signatures in the FBI’s September 15, 2026 update. Record the source version and the telemetry searched when documenting results. [FBI HEAVYGRAM analysis](https://www.ic3.gov/CSA/2026/260915.pdf).
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