Computer Security

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Table of Contents

TOC o “1-3” h z u Introduction PAGEREF _Toc3913593 h 2Discussion PAGEREF _Toc3913594 h 2Principles of key/value databases PAGEREF _Toc3913595 h 2Description of Memcrashed Exploit PAGEREF _Toc3913596 h 4Description of any solution to memcrashed Exploit PAGEREF _Toc3913597 h 5Future importance and effectiveness of memcrashed PAGEREF _Toc3913598 h 7Conclusion PAGEREF _Toc3913599 h 8References PAGEREF _Toc3913600 h 9


Memcached protocol is a well-known mechanism which is required for assisting load balancing of memory demands of large web services in the multiple servers.

It is mainly done so that server does not waste the allocated memory (Bhuyan, Bhattacharyya and Kalita, 2015). It is very effective in nature and is used by various organization like Facebook for managing huge quality of data. The Memcrashed incident comes into picture due to exploitation of Memcached DDoS tool. It is completely written in Python language that allows the user to send forged UDP packets to the server.

It is completely obtained from Shodan. The vulnerability of this particular attack is made possible due to the fact memcached server does not have any kind of authentication on the port 11211 (Bawany, Shamsi and Salah 2017). Any kind of client can establish connection and can generate commands without any kind of hesitation. Memory injection technique can be used for proper amplification which is there in proof of concept (POC) code.

The report mainly focuses on the key principles and value in the database. After that, a list of description has been provided with respect to memcrashed exploit.

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A list of solution has been provided for tackling the memcrashed exploit. The last section of the report deals with future importance and effectiveness for memcrashed.


Principles of key/value databasesKey-value database is considered to be very much effective in nature due to its design in comparison to traditional RDBMS. Schema-less data are generally stored in key-value database. In this particular kind of database, data is stored in the associative arrays (Xu and Liu 2016). Data entries in the associative arrays are provided in the map table. Hash table or dictionary are also known map tables. The associative arrays are nothing but collection of various kind of array and pairs for data which is stored. The main function of associative array is to store the array that binds the key and values in a together way.

Key-Value database is designed in such a way that it can store the required data in document format (David and Thomas 2015). Key-Value database makes use of YAML, XML and lastly JSON for handling of data in much better way.

It comes up with some typical operations like Set and deletes on the given data which is stored in proper(Tapsell, Akram and Markantonakis 2018). Some of the main performance factors of key-value database can be provided below:

Overall response time or latency of data access

Although the overall number of request can be satisfied in given period.

In the scenario of Memcached, it makes use of web service based system which has high number of request of user in the given time. After gaining the user request by the help of key, web services can gain access to the object from nearby cluster (Mousavi and St-Hilaire, 2015). If anyhow the user can gain access to Memcached node, then it will be stated as cache hit. By the help of this particular mechanism, user can gain access to real back-end database which is not needed. All the expensive kind of disk input and output can be avoided.

Memcached server port that is 11211 is known to be open and UDP that is default enabled for vulnerability. It allows the UDP packets in which return is allowed by small bytes which are required to be sent (Ain et al. 2016). When memcached server tries to make reply to the request it can sent back the IP addressed which is spoofed and made possible through packet forgery. The request requires to be modified into a set of request of instruction data which is stored. After that, the data is retrieved in one of the packets. By the help of Shodan API, this particular technique can be used for storing data on large number of vulnerable Memcached server. It will ultimately cause denial of service attack by which it can reach 1 terabyte per second with minimum effort.

Description of Memcrashed Exploit

Memcrashed exploit can take place by forging packets through user datagram protocol. An attacker can gain Memcached denial service vulnerability for initiation of record-breaking DDoS attack (Hoque, Bhattacharyya and Kalita 2016). The biggest problem encountered in this particular attack is forging of the given requirement. For proper working of the attack, the source of Memcached server needs to be spoofed. The general idea behind all the amplification attack is considered to be very similar in nature. An IP-spoofing attacker can send request to the vulnerable UDP based server. UDP server does not understand the request which is forged makes preparation for this particular response (Behal and Kumar 2017). This particular issue comes into picture when large number of response is delivered to an unsuspecting host. It is all about overwhelming of resources and more specifically the network.

DNS amplification based attack makes use of DNS reflection and amplification technique which is needed for forming potent DDoS. Attacker spoof the IP spend a request to the UDP server in this case of Memcached server. At this instance, DNS server responds back to the victim, not to the host (Fouladi, Kayatas and Anarim 2016). It will ultimately result in draining of target resources and resulting denial of service attack. The next part of this attack is amplification of DNS. It is achieved by making use of vulnerabilities in the misconfigured server-based attacks. It is all about the ability to change small query into a large one. The size of query is around 15 bytes in size but it can trigger a response around 134 kb (Dong et al., 2016). It is an example of single packets and monitoring of attacks which result in amplification of packets.

Fig 1: Overview of Memcrashed Exploit

(Source: Wang et al., 2015)

Amplification-based attacks are known to be very much effective in nature. It mainly comes into picture due to fact that response packets are considered to be very much larger in comparison to response packets (Johnson Singh, Thongam and De 2016). This particular technique allows the attacker that comes up with limited IP spoofing for launching attacks and followed by amplification of bandwidth of the attack. Shodan is a powerful tool which exploitation of mass(Johnson Singh, Thongam and De 2016). It mainly provides the exact thing without any kind of scanning of IP along with looking for vulnerable scanner. Shodan can be used for mass exploitation but an API account key is needed for it. Shodan API provides request so that it can be used by Memcached server on the internet platform along with 11211 port which is open (Liu et al. 2018). It will ultimately become an array of different IP address which is easily vulnerable server. Memcached server only requires proper authentication so that it can establish connection and issue required commands.

Description of any solution to memcrashed Exploit

At present, two distinct proof of concept based attack code can be used for Memcached amplification technique that has been released till date. It is very dangerous in nature because any people can make use of this to launch Memcached based DDoS attack. One of the PoC based code is written in Python scripting language that makes use of Shodan based API (Ghi?tte and Doerr 2018). It is needed for updating the list of vulnerable in the Memcached server. On the contrary, the second exploit code is completely written in C programming language. It makes use of list of vulnerable Memcached server. Currently, there are two PoC exploits for Memcached DDoS have been released till date. Various experts around the globe have come up with kill switch mechanism for addressing the Memcached vulnerability (Tapsell, Akram and Markantonakis 2018). Organization around the globe have come up with exploitation issues in the memcached server that allows the user to make necessary modification for stealing data.

DDoS attacks are abusing the server of Memcached as much as possible in current scenario. It is mainly done because of the fact organization have failed to implement some of the basic security practices. In this particular attack, hackers can target the system and can send the query to various server (Westoahu.hawaii.edu2019). Apart from this, the request can go around 50,000 bigger than the query which is provided to the server. In this way, malicious traffic can be provided to the victim site. This particular kind of attack is considered to be reflection of attacks. There are mainly three steps which can be taken for mitigating the attack like

Both the IP address and ports can be mitigated by binding the Memcached in proper way.

User needs to understand the fact that server is accessible by another user easily (Bhuyan, Bhattacharyya and Kalita, 2015). It is mainly done so that it is public less accessible by users.

The fact needs to be taken into account that upstream provider is linked to failure so that the primary one is flooded.

User needs to implement BCP38 & 84 which is anti-spoofing method. It is mainly done so that user can have spoofed attack which is used in DDoS attack(Fouladi, Kayatas and Anarim 2016).

Future importance and effectiveness of men crashed

In the upcoming days, the fact can be taken into account that the problem does not go away easily (Bawany, Shamsi and Salah 2017). It is because of the fact that it is publically exposed and poorly configured server. The attack makes use of shoddily secured Memcached server database server which is required for amplifying against the given target (Hoque, Bhattacharyya and Kalita 2016). UDP can address the spoof of victim and can address a small packet in the Memcached server. It does not require any kind of authenticated traffic need in the given place. Server can easily respond by firing back around 50,000 times in case if the data is received (Xu and Liu 2016). Memcached DDoS attack can work at a time clocking rate of 1.7 tbsp. At present, there are some mitigation techniques like blocking UDP traffic from port number of 11211. It is the default traffic for Memcached server. Apart from this, operators of Memcached server needs to look down their system so that they can avoid any kind of denial of service attack.

On 28 Feb 2018 GitHub has encountered an attack which is around 1.35 terabytes per second (David and Thomas 2015). It is considered to be as one of the most powerful attacks till date. Smaller attacks can occur but these will be testing attack vector which focuses on smaller scale application. GitHub is a well-known example about the fact that how attacks have effect on DDoS attack in their field with the amount of Memcached server in different region of the world (Mousavi and St-Hilaire, 2015). It is expected that there will more DDoS attack in the near future.

In the coming days, there are few steps that should be taken for preventing Memcached server from use in DDoS attack like

UDP port needs to be disabled if it is not in use.

Firewalls servers from the internet platform.

User should not develop by making use of UDP.

ISP need to fix the vulnerable protocols and IP spoofing.


The above pages of the report help in concluding the fact that this report is all about memcrashed attack. DDoS attack is considered to appear suddenly and effective operation of halt operation in the given time. With the passage of time, developers, system administrator, and lastly internet service providers are becoming very much aware of the issue. Memcached server needs to be fixed so that they can reduce the attack vector. This particular attack is considered to be operational plan which is required for handling and recovery of effective downtime and associated damages. The number of vulnerability of Memcached server through Shodan which has dropped from 100,000 to 40,000. In the coming days, it can be expected that the number will continue to drop. For mitigating the attack, a list of steps can be easily taken.


Ain, A., Bhuyan, M.H., Bhattacharyya, D.K. and Kalita, J.K., 2016. Rank Correlation for Low-Rate DDoS Attack Detection: An Empirical Evaluation. IJ Network Security, 18(3), pp.474-480.

Bawany, N.Z., Shamsi, J.A. and Salah, K., 2017. DDoS attack detection and mitigation using SDN: methods, practices, and solutions. Arabian Journal for Science and Engineering, 42(2), pp.425-441.

Behal, S. and Kumar, K., 2017. Characterization and Comparison of DDoS Attack Tools and Traffic Generators: A Review. IJ Network Security, 19(3), pp.383-393.

Bhuyan, M.H., Bhattacharyya, D.K. and Kalita, J.K., 2015. An empirical evaluation of information metrics for low-rate and high-rate DDoS attack detection. Pattern Recognition Letters, 51, pp.1-7.

David, J. and Thomas, C., 2015. DDoS attack detection using fast entropy approach on flow-based network traffic. Procedia Computer Science, 50, pp.30-36.

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Ghi?tte, V. and Doerr, C., 2018, August. How Media Reports Trigger Copycats: An Analysis of the Brewing of the Largest Packet Storm to Date. In Proceedings of the 2018 Workshop on Traffic Measurements for Cybersecurity (pp. 8-13). ACM.

Hoque, N., Bhattacharyya, D.K. and Kalita, J.K., 2016, January. A novel measure for low-rate and high-rate DDoS attack detection using multivariate data analysis. In 2016 8th International Conference on Communication Systems and Networks (COMSNETS) (pp. 1-2). IEEE.

Johnson Singh, K., Thongam, K. and De, T., 2016. Entropy-based application layer DDoS attack detection using artificial neural networks. Entropy, 18(10), p.350.

Liu, Z., Jin, H., Hu, Y.C. and Bailey, M., 2018. Practical proactive DDoS-attack mitigation via endpoint-driven in-network traffic control. IEEE/ACM Transactions on Networking, 26(4), pp.1948-1961.

Mousavi, S.M. and St-Hilaire, M., 2015, February. Early detection of DDoS attacks against SDN controllers. In 2015 International Conference on Computing, Networking and Communications (ICNC) (pp. 77-81). IEEE.

Tapsell, J., Akram, R.N. and Markantonakis, K., 2018. An evaluation of the security of the Bitcoin Peer-to-Peer Network. arXiv preprint arXiv:1805.10259.

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