Targeted DDoS series: When short attacks pack a punch

Within the space of a few days, Link11 observed a wave of DDoS attacks that stood out – not for their duration or scale, but for their surgical precision. A company in the digital entertainment sector was attacked nine times. Rather than relying on prolonged overload, the attackers opted for a “hit-and-run” strategy: short bursts of traffic, each lasting only 5-10 minutes, but reaching peak loads of up to 1 Tbit/s. The attacks were distributed over six days and consistently targeted two specific IP addresses – at different times and with high throughput.

What made this campaign remarkable wasn’t just the raw traffic volume, but the method, which was brief, focused, and effective. The limited duration of each attack made analysis challenging, while still revealing clear strategic intent.

The attacks had three key characteristics:

Short but intense: Each DDoS attack lasted only a few minutes yet unleashed massive data streams ranging from gigabit to terabit levels. The cumulative traffic volume spanned several hundred terabytes, with spikes up to one trillion bits per second (Tbit/s), compressed into narrow time windows.

Recurring and staggered: Rather than sustained pressure, the attacks occurred multiple times per day at different times. The rapid surge in traffic – from zero to several hundred Gbit/s within seconds ("fast ramping") – left little time for traditional mitigation strategies to respond, allowing for maximizing disruption with minimal exposure.

Technically varied, strategically controlled: Initially, the attackers used UDP floods on port 443 to disrupt encrypted traffic (QUIC/HTTPS). Over time, the tactics shifted:

• Initially, UDP floods were used on port 443 to specifically disrupt encrypted web communication (QUIC/HTTPS).
• Follow-up attacks added TCP 80 floods to maintain high bandwidth.
• Later waves introduced variable-size packets on TCP ports 80 and 443 with a lower volume (~200 Gbit/s) but more complex behavior.
• One wave targeted UDP 123 (NTP), a rarely used protocol often seen in reflection attacks. This traffic was limited to 40 Gbit/s and consisted of small packets and random target ports.
• The campaign concluded with a return to the initial pattern of high-bandwidth floods on UDP and TCP 443 using large packets, varied source ports, and IP addresses.

Packet analysis revealed a strategic evolution: the initial waves featured consistent packet sizes, which is typical of reflective attacks, while later stages showed mixed packet sizes, likely to bypass signature-based defenses.

The distributed origin of the traffic, spanning various source autonomous system numbers (ASNs) and entering through all major Link11 nodes, indicates a high level of load balancing and possibly spoofed or compromised IP addresses. This makes attribution difficult and suggests a large, globally dispersed botnet.

Informed and deliberate targeting

Traffic patterns strongly suggest that the attacker had prior knowledge of the target’s infrastructure, especially its HTTPS services. The timing of the attack, the protocol selected, and the specificity of the target point to a deliberate effort to disrupt key digital services with minimal noise.

The overall strategy suggests:

• The attacker understood the architecture and services in use.
• Attack windows and protocol choices were optimized for disruption and efficiency.
• A global botnet infrastructure enabled wide distribution across multiple carriers, possibly to exploit regional weaknesses or saturate key transit nodes.

Likely motivation: Competition, not geopolitics

Given the target’s position in the digital entertainment sector, which is frequently hit by financially motivated cyberattacks, it is plausible that the attacker’s goal was commercial disruption. Attack timing that aligns with peak usage further supports this theory.

Additional insights:

Beyond the immediate impact, the campaign reveals important trends in modern DDoS behavior:

• Botnet preparation: In the days leading up to the main wave, smaller probing patterns were observed – likely reconnaissance or test phases.
• Adaptive tactics: Protocols and source behavior shifted between attacks, suggesting that the attacker adjusted in response to mitigation attempts.
• Operational efficiency: The use of short bursts and freely accessible tools (e.g., open proxies, spoofing, and low-cost botnets) indicates a cost-effective attack model with a low barrier to entry.

Implications for defense

Such attacks are difficult to detect and even more difficult to defend against. Their brevity complicates forensic tracing, and their variability poses a challenge to automated filters. For attackers, their effectiveness is undeniable.

Robust defenses should include:

• Dynamic detection that analyzes not only volume, but also packet behavior and timing.
• Behavioral analysis at both the network and application layers.
• Geographical and systemic redundancy in mitigation infrastructure.
• Preparedness for specific DDoS patterns (e.g., UDP 443 floods, TCP reflection) supported by tailored incident response playbooks.

Conclusion: Precision is the new threat dimension

This campaign underscores a growing shift in DDoS strategy. Attackers no longer need overwhelming force; intelligent timing, protocol agility, and infrastructure knowledge are sufficient to cause significant disruption.

Effective defense requires more than just bandwidth. It demands intelligent, adaptive systems that can analyze traffic and recognize behavior in real time – before service interruptions occur.

Would you like to know how your company is equipped to defend against tactically sophisticated DDoS attacks? Our experts will support you in analyzing, planning, and implementing effective protection solutions.

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