1. Internet of Things
Amr El Mougy
Alaa Gohar

2. IoT Security – part 2

3. RPL Security

4. Security Features
Defines protection for all types of control messages (DIO, DAO, DIS, DAO-ACK)
Three security levels are identified
Security field identifies the cryptographic suite used and the security level
Services include:
Integrity and authenticity
Confidentiality
Key management
Protection against replay attacks

5. Implementing Security Services
Integrity can be provided using a MAC-32 or MAC-64 codes
RSA Digital signatures based on SHA-256 also supported
Confidentiality is supported based on AES/CCM.
The entire RPL packet falls within the scope of protection (except the immutable fields of the header)
Security level is specified in the LVL field
Replay attacks are prevented using a counter and timestamp
Sensors can issue a challenge/response message to check the consistency of the counter value at a different node

6. Key Identifier Mode Three types of keys are defined:
Group symmetric key
Symmetric key per pair of nodes
Public key for digital signatures
Key index field allows identification of which key to be used

7. Security Modes Three modes are defined:
Unsecured: default mode. No security is applied to RPL messages
Preinstalled: a pre-configured symmetric is used by a device to join an RPL instance as host or router. The key supports confidentiality, integrity, and data authentication
Authenticated: appropriate for routers. The preinstalled key is used to join the RPL and then to obtain a different key from a key authority, which is responsible for authenticating the router.
Authenticated mode can only be supported using public key cryptography. However the standard does not specify how it can be implemented.

8. CoAP Security

9. Security Services
CoAP doesn’t have built in security features but defines bindings to Datagram Transport Layer Security (DTLS)
DTLS supports similar services to TLS but for UDP packets
This means security is supported at the transport layer rather than the application layer
Security services include:
Confidentiality, authentication, and integrity: based on AES-CCM
Non-repudiation: based on elliptic curve digital signatures (public keys)
Protection against replay attacks: using a different nonce for each CoAP packet

10. Security Modes CoAP defines four security modes to be enforced by DTLS
NoSec: completely unsecured transmissions
PreSharedKey: sensing devices are pre-programmed with a symmetric key. Devices may use one key for every destination or use group keys for a set of devices
RawPublicKey: mandatory in CoAP. Devices use a pre-programmed public key to avoid needing a certificate authority. The public keys are used for authentication
Certificates: public keys are authenticated using certificated based on public key infrastructure
Device authentication is supported in RawPublicKey and Certificate modes using elliptic curve digital signatures
Key exchange can also be done using elliptic curve Diffie-Hellman
A DTLS handshake is required before data exchange

11. ICN Security

12. ICN Challenges
In ICN, publishers may not send their content directly to receivers
ICN changes the security model from securing endpoints to securing objects
Thus, ICN may suffer from all new forms of attacks in addition to legacy ones
In-network caching is heavily used
Since content may come from any place in the network, security cannot be bound to endpoints
Security is applied to the content itself

13. Security Levels
The severity of ICN attacks can be calculated by looking at the following metrics:
Block content retrieval
Access user request
Cache pollution
Misrouting
Request timeout
Number of affected nodes
Geographical distribution of attacked networks
Remote exploitation
Availability of environment that was attacked
How difficult is it to fix the attack

14. Types of ICN Attacks

15. 1. Naming Attacks
The attacker tries to monitor/censor Internet usage by blocking delivery of content or viewing who request this content
ICN makes information flow more visible to attackers
For the attacker to monitor user requests they have to hijack an ICN node because packets do not carry host identifiers
This is not necessary for content filtration/deletion
Naming attacks can be classified into watchlist and sniffing attacks

16. Naming Attacks Watchlist
The attacker tries to delete a specific list of content names
The attacker monitors network links to perform real-time traffic filtering
The attacker either deletes (or monitors) the user’s request or deletes the content itself

17. Naming Attacks Sniffing
The attacker does not have a specific list but monitors packets to check for content that includes particular keywords (Real Madrid, Zamalek, Lady Gaga)
Any packet containing these keywords are marked and filtered out
Main difference is that the attacker does not have a predefined list of content names but does real-time analysis of traffic

18. Impact of Naming Attacks
Naming attacks can cause the following:
Censorship: specific content never delivered
Privacy: the attacker learns the interests of a large number of users because ICN allows access to user requests
Denial of service: the attacker blocks access to particular requests (for example a set of users)

19. 2. Routing Related Attacks
Routing in ICN is asynchronous: publishers and subscribers do not act at the same time
Thus, the corresponding states at the routers have to be consistent, which is not easy
Attacks in this category include spoofing attacks to cause the consistency to fail
It also includes DDOS attacks that consumes resources

20. Routing Related Attacks
DDOS
Resource Exhaustion
Infrastructure
Source
Mobile Blockade
Flooding
Timing
Routing Related Attacks
Spoofing
Jamming
Hijacking
Interception

21. Routing Related Attacks
DDOS
Infrastructure attacks: the attacker sends a large number of available/unavailable requests
The network keeps propagating these requests towards the source, consuming resources
ICN mitigates this attack by propagating requests to multiple resources

22. Routing Related Attacks
DDOS
Source attacks: the attacker targets a specific publisher and sends a very large number of requests
Mobile blockade: the attacker sends a large number of requests while traversing the network, thereby contaminating a particular geographical region
Timing attack: the attacker increases the timeout of requests to violate the router’s consistency. These leads to larger delays in responses
Mobile blockade

23. Routing Related Attacks
Spoofing
Jamming attacks: the attacker sends a large number of bogus requests. The network replies but no one is waiting to receive
Hijacking attack: the attacker masquerades as a trusted publisher and announces invalid routes for any content. Requests sent on these invalid routes will not be answered.
Interception attacks: man in the middle. The attacker announces invalid routes and the content is sent to the attacker, who then forwards it to the users, violating their privacy
Hijacking
Interception
Jamming

24. 3. Caching Related Attacks
Caching is a very important component in ICN
It is vulnerable to pollution or corruption
Caching attacks can be classified into time analysis, bogus announcements, and cache pollution attacks

25. Caching Related Attacks
Time Analysis
The attacker monitors traffic of a user and measures the response time between cached and uncached content
When a legitimate user requests content for the first time it will be obtained from the publisher in time T1 + T2
If an adversary requests the same content later it will be returned in only T1 because it was cached. The attacker uses this information to learn that a user has requested the content before
1- A user requests for ICN content named (x).
2- and 3- ICN routers try to find the content (x).
4- and 5- ICN routers forward the content (x) to the requested user.
6- The user retrieves the content (x) in total time T1+T2.
7- An adversary requests for the content (x).
8- The adversary retrieves the content (x) in time T2 only, as routers cache the content.

26. Caching Related Attacks
Bogus Announcements
The attacker sends many content updates at a rate greater than the convergence time of the routers to violate caching and routing systems
ICN routers will not be able to respond properly to requests while these bogus announcements are being received

27. Caching Related Attacks
Cache Pollution
Unpopular requests: the attacker only sends requests for content that is unpopular. Requires a prior knowledge of content popularity
Random requests: the attacker requests content at random to fill the cache with content that may not necessarily be popular

28. Random requests (normal)
1- User1 requests for ICN content named (x).
2- R1 router tries to find the content (x).
3- R1 retrieves the content from ICN network.
4- R1 caches the content (x).
5- User1 retrieves the content (x).
6- User2 requests the same content (x) via R2 router.
7- R2 tries to find the closest copy, which exists in R1 router.
8- R1 sends the content to R2 router.
9- R2 caches the content (x).
10- User2 retrieves the content (x).
Random requests (normal)
1- User1 requests for ICN content named (x).
2- R1 router tries to find the content (x).
3- R1 retrieves the content from ICN network.
4- R1 caches the content (x).
5- User1 retrieves the content (x).
6- An attacker sends a large number of random/unpopular requests to violate the cache.
7- User2 requests the same content (x) via R2 router.
8- R2 tries to find the closest copy and sends request to R1.
9- R1 router tries to find the content (x).
10- R1 retrieves the content from ICN network.
11- R1 caches the content (x).
12- R1 sends the content to R2.
13- R2 caches the content (x).
14- User2 retrieves the content (x).
Random requests (attacked)

29. 4. Miscellaneous Attacks
Attacks that aim to degrade ICN services or gain unauthorized access
Can be classified into packet mistreatment, breaching signer’s key, and unauthorized access
Packet mistreatment: the attacker gains access to an ICN node or link and modifies or replays packets
The requester may receive the reply to a request several times or the attacker may generate content on behalf of the user
Can lead to congestion of links or reduced throughput (or DOS)
Unauthorized access: the attacker gains access to a service he/she is not authorized to. Here the attacker makes use of any available content copy to gain access
Here the attacker may capture all user requests and track all their activities

30. Miscellaneous Attacks Breaching Signer’s key
The attacker somehow obtains the private key of the publisher used to sign packets
Using this key, the attacker can generate any content and it will be trusted by the users
An attacker requests for ICN content named (x).
The attacker retrieves the content (x) that contains signer’s public key and signature, which can be used with the content itself to determine the signer’s key.