Russia Charges Telegram Founder: The C2 Implications & OpSec
Saw the breaking news about the FSB charging Pavel Durov for failing to remove prohibited content (channels/bots). While the legal/political side is messy, this highlights a massive pain point for us in Blue Teams: the continued abuse of Telegram as C2 infrastructure.
We've seen countless campaigns (like the teleshim/mixedkey mentioned recently) leveraging Telegram bots. The platform's ubiquity makes it a nightmare to block without disrupting business ops.
If you are auditing your environment for leaked bot tokens often found in repos, here is a quick Python regex check to identify valid formats:
import re
def find_telegram_tokens(text):
# Regex for standard Bot Tokens: 123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11
pattern = r'\d{8,10}:[A-Za-z0-9_-]{35}'
return re.findall(pattern, text)
# Example usage in a scan script
log_data = "bot_token: 110201543:AAHdqTcvCH1vGWJxfSeofSAs0K5PALDsaw"
print(find_telegram_tokens(log_data))
Network-wise, blocking MTProto is tricky because it mimics HTTPS traffic. If you aren't blocking it, how are you hunting for malicious beaconing?
Are you folks enforcing full blocks on Telegram, or are you relying on behavioral analytics to catch the C2 traffic?
We moved from monitoring to a full block on the guest VLAN and strict allow-listing for internal users. The noise was too much. Too many devs were pasting tokens into public repos, and we kept seeing droppers using Telegram for exfiltration. It broke a few hearts, but the risk reduction was worth it.
Blocking isn't an option for our sales team. We rely on NetFlow/Enrichment to spot anomalies. Specifically, we look for small, repetitive packet sizes to known Telegram CDN ranges during off-hours. It’s not perfect, but it catches the 'heartbeat' style check-ins of common malware families.
Does anyone have a reliable list of current Telegram CIDR ranges? They seem to change frequently to bypass GEO-blocks, which makes maintaining firewall rules a pain. I've been using a community Github list but it's not always up to date.
Relying solely on CIDR lists is a losing battle given how aggressively Telegram rotates infrastructure. I’ve shifted focus to TLS fingerprinting. The Telegram client has a distinct JA3 signature that separates it from generic browser traffic.
If you're using Zeek, query for specific mtproto fingerprints or non-standard TLS extensions. It’s often more reliable than packet size analysis for reducing false positives with other chat apps.
zeek event ssl_established(c: connection) { if (c$ssl$service == "telegram") { print fmt("Telegram traffic detected from %s", c$id$orig_h); } }
Has anyone noticed a shift towards MTProto over TCP 443 to bypass standard SSL inspection proxies?
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