  While collaborative systems provide convenience to our lives, they also face
many security threats. One of them is the Low-rate Distributed
Denial-of-Service (LDDoS) attack, which is a worthy concern. Unlike volumetric
DDoS attacks that continuously send large volumes of traffic, LDDoS attacks are
more stealthy and difficult to be detected owing to their low-volume feature.
Due to its stealthiness and harmfulness, LDDoS has become one of the most
destructive attacks in cloud computing. Although a few LDDoS attack detection
and defense methods have been proposed, we observe that sophisticated LDDoS
attacks (being more stealthy) can bypass some of the existing LDDoS defense
methods. To verify our security observation, we proposed a new Feint-based
LDDoS (F-LDDoS) attack strategy. In this strategy, we divide a Pulse Interval
into a Feinting Interval and an Attack Interval. Unlike the previous LDDoS
attacks, the bots also send traffic randomly in the Feinting Interval, thus
disguise themselves as benign users during the F-LDDoS attack. In this way,
although the victim detects that it is under an LDDoS attack, it is difficult
to locate the attack sources and apply mitigation solutions. Experimental
results show that F-LDDoS attack can degrade TCP bandwidth 6.7%-14% more than
the baseline LDDoS attack. Besides, F-LDDoS also reduces the similarities
between bot traffic and aggregated attack traffic, and increases the
uncertainty of packet arrival. These results mean that the proposed F-LDDoS is
more effective and more stealthy than normal LDDoS attacks. Finally, we discuss
the countermeasures of F-LDDoS to draw the attention of defenders and improve
the defense methods.
