# The Security of Big Data in Fog-Enabled IoT Applications Including Blockchain: A Survey
## 5 Fog Computing Security Challenges  
Cloud computing has significant weaknesses to protect its computing framework and storage from malicious attacks [62; 63]. Some of the security and privacy threats are summarized in Table 1. Fog-based architectures are more secure than cloud architectures for several reasons including less dependency on the Internet and possible storage and information exchange between the cloud and its users in non-real-time [64]. Fog-enabled IoT systems employ various networks for interconnecting all \begin{table}
\begin{tabular}{p{113.8 pt} p{284.5 pt}} \hline \hline
**Attacks** & **Description** \\ \hline Wormhole [53] & Initial attacked node forms a path by colluding with other nodes to transfer malicious packets. The path formed among conspiring nodes is called wormhole. \\ \hline Blackhole [54] & A malicious node intervenes in route discovery to be a part of path. It then drops the packets instead of forwarding them. Some blackholes attack the received packets before forwarding. \\ \hline Greyhole [54] & A modified version of blackhole attacks. Data are dropped by the attacking node, but it tells the router that data are transmitted. This attack is difficult to detect by the router as it shows end-to-end connectivity. \\ \hline Selective forwarding [55] & Selective data packets that are required to be transmitted are dropped by nodes resulting in network performance degradation. \\ \hline Local repair [46] & Destabilizing the network and draining neighbor nodes battery by sending false link repair messages. It reduces packet delivery increases end-to-end delays. \\ \hline Route cache poisoning [56] & It involves the alteration of route tables by malicious nodes to poison route caches to other nodes. \\ \hline Sybil [47] & Assumptions of nodes to have multiple identities over the network to create confusion and disruption, which opens the opportunity for malicious nodes to operate. \\ \hline Sinkhole [57] & Malicious node pretends to be the optimal route to the destination node by sending false messages to the initiator node, thus after receiving traffic, it alters the routing and other data to complicate the topological structure of the network. \\ \hline Hello flood [58] & The attacker node broadcasts links to other nodes. The unsuspecting nodes accept that link and consider the attacker node to be the neighbor node. The unsuspecting node start sending packets that are actually wasted as the adversary node is far away and not the neighbor. This creates a routing loop within the network. \\ \hline Neighbor [54] & The neighbor node considers the attacking node (while broadcasting DIO messages with no DIO details) as a newly joined node, which could be a parent node, but this node is out of reach when the neighbor node tries to select it as a parent node. \\ \hline Version number [54] & The attacker node alters its version number in DIO messages and broadcasts to neighbor nodes. This results in routing loops in the network, which disrupt the network topology and deplete nodes energy resources. \\ \hline Modification [59] & Malicious nodes take advantage of no trust levels being measured in the ad-hoc networks to engage in discovering, altering and disrupting the routing in the network. This attack causes traffic redirection and DoS attacks by modifying the protocol messages. \\ \hline Fabrication [60] & Creates forged routing information using routing table overflow attacks, resource consumption and fake route error messages. \\ \hline Byzantine [61] & Aims to decline the network services; the attacker node selectively drops route packets, which create routing loops and send forward those route packets through non-optimal paths. \\ \hline Location spoofing [61] & Pretends to be the nearest destined node to disrupt normal network protocol operations. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Internal attacks on fog-based IoT routing. the participating devices, such as wireless and mobile core networks making them potential targets for any attack [65].