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Martin Hell

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The terms threat, vulnerability and weakness are often used in cybersecurity. Understanding the difference between these terms is important. It allows organizations to correctly implement, document and assess their cybersecurity activities and controls. Here, we take a closer look at security weaknesses. While threat and vulnerability have rather clear definitions in cybersecurity, this is not the case for a weakness. Commonly used glossaries, such as RFC 4949 and the NIST glossary do not define the term weakness. On the other hand, it is very often used as part of the vulnerability definition. A vulnerability is a weakness that can be exploited by an attacker. Thus, a weakness is an error, typically in the software code, that might lead to a vulnerability. This happens when it can be exploited. Software weaknesses are often discussed and defined in the context of the Common Weaknesses Enumeration (CWE). This is a “community-developed list of…

The terms threat, vulnerability and weakness are often used in cybersecurity. Understanding the difference between these terms is important. It allows organizations to correctly implement, document and assess their cybersecurity activities and controls. Here, we take a closer look at security threats. Defining a security threat Looking in the literature, we can find several definitions of the term. Two rather short and concise can be found in documents from IETF and NIST. In RFC 4949, IETF defines a threat as A potential for violation of security, which exists when there is an entity, circumstance, capability, action, or event that could cause harm.RFC 4949 NIST, in SP800-160, defines it as An event or condition that has the potential for causing asset loss and the undesirable consequences or impact from such loss.NIST SP800-160 Cyber threats are sometimes incorrectly confused with vulnerabilities. Looking at the definitions, the keyword is “potential”. The threat is…

The terms threat, vulnerability and weakness are often used in cybersecurity. Understanding the difference between these terms is important. It allows organizations to correctly implement, document and assess their cybersecurity activities and controls. Here, we take a closer look at vulnerabilities. Defining a vulnerability The United Nations, defines a vulnerability as “…the inability to resist a hazard or to respond when a disaster has occurred”. United Nations This is a very general definition and is not restricted to cybersecurity. We can see it as a property of an asset that makes it susceptible to damage. This property can be inherent in the design. It can also be a result of tradeoffs that have to be made, or it can be the result of actual design mistakes. Let us look at the more specific case of (cyber)security vulnerabilities. There are several different, but often similar, definitions in the literature. We look…

The problems with repeated keystream in stream ciphers Repeated keystream can sometimes be devastating when using stream ciphers. The Capture the Flag event co-organized by Debricked at Lund University included examples of this problem. Stream ciphers try to mimic the One Time Pad (OTP), but without the inherent drawbacks of a cipher that requires a key the size of the plaintext. Instead, the stream cipher expands a short key (80-256 bits) to a long sequence through the use of a keystream generator. The keystream generator outputs keystream bits (or words) based on the value of an internal state, a key and an initialization vector (IV). The exact definition of this function varies between stream ciphers and often the key and IV is only used to initialize the internal state. The output then only depends on the current internal state. The goal of an attack could be to either compute the…

CTF-Event with Lund University Debricked, in cooperation with the Department of Electrical and Information Technology, Lund University, hosted a Capture the Flag (CTF) competition for students at the university. The event attracted more than 50 students from 8 different programs, forming in total 17 teams. The evening consisted of food, beverages, snacks, but most importantly cybersecurity related challenges for the students to dive into and solve. The challenges were tailored to be suitable for both beginners and for more experienced people and all teams managed to solve at least some problems. The CTF was given in jeopardy style, where the groups could choose from a collection of different challenges. The challenges covered well known CTF topics, including cryptography, reverse engineering, pwning, web security and a miscellaneous category. The latter had challenges such as lockpicking, password attacks and hardware security. After a short presentation and walkthrough of rules and hints, the…