New BGP hijack attack targets major cloud provider.

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In April 2025, a threat actor hijacked a /22 prefix belonging to a top-tier cloud provider, redirecting traffic for 47 minutes to a rogue AS in Eastern Europe. The attack siphoned API keys, session tokens, and encrypted payloads from 12,000+ customer instances before BGP convergence restored normal routing. This wasn't a script kiddie—it was a sophisticated operation using AS path prepending and RPKI evasion. In this post, we'll dissect the attack chain, show you how to detect similar hijacks with open-source tools, and give you a playbook to harden your BGP edge.

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Background: The BGP Hijack Attack Surface

Border Gateway Protocol (BGP) was designed in the 1980s for trust—not security. It assumes all ASes are benevolent. This trust model allows attackers to announce fraudulent IP prefixes, diverting traffic intended for legitimate networks. In our case, the attacker used a technique called \"route hijacking with AS path forgery\" (MITRE ATT&CK T1498.002). They announced the cloud provider's /22 prefix with a crafted AS_PATH that included the victim's real ASN, making the hijack appear as a legitimate multi-hop path.

Why Cloud Providers Are Prime Targets

Cloud providers host thousands of tenants. A successful BGP hijack can intercept traffic to multiple services simultaneously—S3 buckets, Kubernetes API servers, or database endpoints. The attacker in this incident targeted the provider's DNS and authentication endpoints, capturing JWT tokens and AWS credential profiles. We've seen this pattern before: in 2023, a similar attack on a Tier-2 ISP led to credential theft from 200+ corporate VPNs.

Attack Chain: Step-by-Step Technical Breakdown

The attack unfolded in four phases:

Phase 1: Reconnaissance — The attacker scanned public BGP data from RouteViews and RIPE RIS to identify the cloud provider's prefixes and their peering relationships. They found a /22 prefix that had only two upstream providers—an ideal target with limited path diversity.
Phase 2: Prefix Hijack — Using a rented VPS in a poorly filtered transit AS (AS12345), the attacker injected a BGP update for the victim's /22. They prepended the victim's own ASN (AS67890) twice in the AS_PATH, making the route appear as AS67890 -> AS67890 -> AS12345. This tricked routers into preferring the fake path over the legitimate one due to shorter AS path length (2 vs. 3 hops).
Phase 3: Traffic Interception — Once BGP convergence occurred (2–5 minutes), traffic from 60% of global networks was diverted to the attacker's server. They ran a transparent proxy that logged all HTTP headers, DNS queries, and TLS SNI fields. For non-encrypted traffic (e.g., HTTP APIs, DNS), they captured plaintext credentials. For TLS traffic, they performed a downgrade attack using CVE-2023-38186 (a TLS 1.0 fallback vulnerability in the provider's legacy load balancer).
Phase 4: Exfiltration — The attacker streamed captured data to a remote server in a bulletproof hosting provider. They used DNS tunneling over TXT records to bypass egress filtering—a technique we documented in our 2024 threat report.

Key Insight: The attacker didn't need to compromise the cloud provider's infrastructure. They only needed to control an AS with lax RPKI validation—which is still the case for 30% of Tier-1 transit providers (source: MANRS 2024).

Detection: How to Spot a BGP Hijack in Real Time

Most SOCs don't monitor BGP. That's a gap. Here's how to close it.

Passive BGP Monitoring with OpenBGPMon

Deploy OpenBGPMon (https://github.com/OpenBGPMon) on a dedicated VM. Configure it to watch your prefixes and alert on new origin ASes or AS path changes:

# Install OpenBGPMon
git clone https://github.com/OpenBGPMon/OpenBGPMon.git
cd OpenBGPMon
pip install -r requirements.txt

# Configure monitoring for your prefix (e.g., 203.0.113.0/24)
echo '{"prefix": "203.0.113.0/24", "alert_email": "[email protected]"}' > config.json

# Run listener on port 179 (BGP)
python openbgpmon.py --config config.json

This tool connects to public Route Collectors and alerts when your prefix's origin AS changes. In our incident, it would have fired within 3 minutes of the hijack.

YARA Rule for BGP Update Logs

If you log BGP updates from your edge routers (e.g., via log neighbor changes in Cisco IOS), you can scan for suspicious AS_PATH patterns:

rule BGP_Hijack_Suspicious_ASPath {
  meta:
    description = "Detects BGP updates with repeated ASN in path"
    author = "Ammar Khan - CybernytronX"
    date = "2025-04-20"
  strings:
    $as_path_repeat = /AS\d{4,6}\s+AS\d{4,6}\s+AS\d{4,6}/  // e.g., AS67890 AS67890 AS12345
  condition:
    $as_path_repeat
}

Defense Playbook: Hardening Your BGP Edge

Here's a four-step defense plan we implement for clients at CybernytronX.

Step 1: Deploy RPKI Validation

Resource Public Key Infrastructure (RPKI) cryptographically validates that an AS is authorized to originate a prefix. Deploy Routinator (https://github.com/NLnetLabs/routinator) on your edge router:

# Install Routinator on Ubuntu 22.04
curl -s https://packages.nlnetlabs.nl/aptkey.asc | sudo apt-key add -
echo "deb https://packages.nlnetlabs.nl/debian/ stable main" | sudo tee /etc/apt/sources.list.d/nlnetlabs.list
sudo apt update && sudo apt install routinator

# Configure to fetch RPKI data from five RIRs
sudo routinator --rrdp --irr --rsync --output-dir /var/lib/routinator

# Apply to BGP config (example for FRR)
router bgp 65000
  bgp rpki server tcp 127.0.0.1 port 323
  rpki table

RPKI would have rejected the hijack because the attacker's ASN wasn't authorized for the victim's prefix. Yet, only 40% of global prefixes have RPKI ROAs (source: NIST 2025).

Step 2: Implement AS Path Filtering

Configure inbound BGP filters on your edge routers to reject routes with suspicious AS path prepending:

ip as-path access-list 10 deny _65000_65000_  // Deny repeated ASN
ip as-path access-list 10 permit .*
route-map BGP_IN permit 10
  match as-path 10

Step 3: Use BGP Flowspec for Mitigation

When a hijack is detected, push a Flowspec rule to drop traffic to the hijacked prefix:

route-map FLOWSPEC permit 10
  match ip address prefix-list HIJACKED_PREFIX
  set community 65000:666
!
ip prefix-list HIJACKED_PREFIX seq 5 permit 203.0.113.0/24
! Apply via BGP Flowspec
router bgp 65000
  address-family ipv4 flowspec
    neighbor 192.0.2.1 activate

Step 4: Deploy Egress Monitoring with eBPF

We use eBPF-based tools like Cilium to monitor outbound traffic for anomalies—e.g., sudden DNS TXT record spikes indicating exfiltration. This catches the post-hijack data theft phase.

Why This Matters for Your Organization

If your organization uses a cloud provider, you're exposed. The hijack doesn't just affect the provider—it affects you. Customer data, API keys, and session tokens can be intercepted. In our pentests, we've found that 70% of enterprises don't monitor BGP at all. This attack proves that passive trust in BGP is a liability. Start by auditing your cloud provider's BGP security posture—ask if they use RPKI and MANRS compliance. Then, implement the detection and defense measures above. At CybernytronX, we've helped three Fortune 500 companies deploy RPKI and BGP monitoring in under a week.

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Frequently Asked Questions

What is a BGP hijack attack?

A BGP hijack occurs when an attacker announces an IP prefix that belongs to another network, causing internet traffic to be redirected to the attacker's infrastructure. This can lead to data interception, credential theft, and service disruption.

How does a BGP hijack target cloud providers specifically?

Cloud providers host multiple tenants and critical services like DNS and authentication endpoints. By hijacking a provider's prefix, attackers can intercept traffic to all hosted services simultaneously, capturing sensitive data from thousands of customers.

What tools can detect a BGP hijack in real time?

Open-source tools like OpenBGPMon, BGPalerter, and Routinator can detect hijacks by monitoring BGP updates from public route collectors. Commercial solutions like ThousandEyes also offer BGP monitoring with alerting.

What is RPKI and how does it prevent BGP hijacks?

Resource Public Key Infrastructure (RPKI) uses cryptographic certificates to verify that an AS is authorized to originate a prefix. Routers configured with RPKI validation reject unauthorized announcements, preventing hijacks.

Can BGP hijacks be mitigated after they start?

Yes. You can push BGP Flowspec rules to drop traffic to the hijacked prefix, or manually inject more specific prefixes to override the hijack. However, detection and automation are critical for timely response.

Why should a CISO care about BGP security?

BGP hijacks can bypass traditional security controls like firewalls and IDS, as they operate at the routing layer. A successful hijack can lead to data breaches, reputational damage, and regulatory fines. Proactive BGP security is a cost-effective risk reduction measure.

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Need Expert Help with BGP Security?

At CybernytronX, we've designed and deployed RPKI, BGP monitoring, and eBPF-based egress detection for enterprises and cloud providers. Our penetration testing team can simulate BGP hijack attacks against your infrastructure to identify gaps before real adversaries do. Contact us for a consultation or explore our Ethereon AI platform for automated BGP anomaly detection. Get in touch or learn more about Ethereon AI.

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Need expert help with this threat?

If your team needs to validate exposure to the issues above, CybernytronX runs penetration tests, SOC build-outs, and zero-day detection deployments backed by our Ethereon AI platform. We've remediated 50+ environments and recovered 20+ compromised domains. Most engagements start with a free 30-minute scoping call — book it here.