86 research outputs found
Using honeypots to trace back amplification DDoS attacks
In today’s interconnected world, Denial-of-Service attacks can cause great harm by simply rendering a target system or service inaccessible. Amongst the most powerful and widespread DoS attacks are amplification attacks, in which thousands of vulnerable servers are tricked into reflecting and amplifying attack traffic. However, as these attacks inherently rely on IP spoofing, the true attack source is hidden. Consequently, going after the offenders behind these attacks has so far been deemed impractical. This thesis presents a line of work that enables practical attack traceback supported by honeypot reflectors. To this end, we investigate the tradeoffs between applicability, required a priori knowledge, and traceback granularity in three settings. First, we show how spoofed attack packets and non-spoofed scan packets can be linked using honeypot-induced fingerprints, which allows attributing attacks launched from the same infrastructures as scans. Second, we present a classifier-based approach to trace back attacks launched from booter services after collecting ground-truth data through self-attacks. Third, we propose to use BGP poisoning to locate the attacking network without prior knowledge and even when attack and scan infrastructures are disjoint. Finally, as all of our approaches rely on honeypot reflectors, we introduce an automated end-to-end pipeline to systematically find amplification vulnerabilities and synthesize corresponding honeypots.In der heutigen vernetzten Welt können Denial-of-Service-Angriffe große Schäden verursachen, einfach indem sie ihr Zielsystem unerreichbar machen. Zu den stärksten und verbreitetsten DoS-Angriffen zählen Amplification-Angriffe, bei denen tausende verwundbarer Server missbraucht werden, um Angriffsverkehr zu reflektieren und zu verstärken. Da solche Angriffe jedoch zwingend gefälschte IP-Absenderadressen nutzen, ist die wahre Angriffsquelle verdeckt. Damit gilt die Verfolgung der Täter bislang als unpraktikabel. Diese Dissertation präsentiert eine Reihe von Arbeiten, die praktikable Angriffsrückverfolgung durch den Einsatz von Honeypots ermöglicht. Dazu untersuchen wir das Spannungsfeld zwischen Anwendbarkeit, benötigtem Vorwissen, und Rückverfolgungsgranularität in drei Szenarien. Zuerst zeigen wir, wie gefälschte Angriffs- und ungefälschte Scan-Datenpakete miteinander verknüpft werden können. Dies ermöglicht uns die Rückverfolgung von Angriffen, die ebenfalls von Scan-Infrastrukturen aus durchgeführt wurden. Zweitens präsentieren wir einen Klassifikator-basierten Ansatz um Angriffe durch Booter-Services mittels vorher durch Selbstangriffe gesammelter Daten zurückzuverfolgen. Drittens zeigen wir auf, wie BGP Poisoning genutzt werden kann, um ohne weiteres Vorwissen das angreifende Netzwerk zu ermitteln. Schließlich präsentieren wir einen automatisierten Prozess, um systematisch Schwachstellen zu finden und entsprechende Honeypots zu synthetisieren
Die gesellschaftliche Konstruktion einer neuen Technik. Legitimationsstrategien zur Durchsetzung der bemannten Raumfahrt als Beispiel
Die deutsche Pläne zur bemannten Raumfahrt werden einer umfassenden Kosten-Nutzen-Abschätzung unterzogen
teEther: Gnawing at Ethereum to Automatically Exploit Smart Contracts
Cryptocurrencies like Bitcoin not only provide a decentralized currency, but also provide a programmatic way to process transactions. Ethereum, the second largest cryptocurrency next to Bitcoin, is the first to provide a Turing-complete language to specify transaction processing, thereby enabling so-called smart contracts. This provides an opportune setting for attackers, as security vulnerabilities are tightly intertwined with financial gain. In this paper, we consider the problem of automatic vulnerability identification and exploit generation for smart contracts. We develop a generic definition of vulnerable contracts and use this to build TEE THER, a tool that allows creating an exploit for a contract given only its binary bytecode. We perform a large-scale analysis of all 38,757 unique Ethereum contracts, 815 out of which our tool finds working exploits for—completely automated
BGPeek-a-Boo: Active BGP-based Traceback for Amplification DDoS Attacks
Amplification DDoS attacks inherently rely on IP spoofing to steer attack traffic to the victim. At the same time, IP spoofing undermines prosecution, as the originating attack infrastructure remains hidden. Researchers have therefore proposed various mechanisms to trace back amplification attacks (or IP-spoofed attacks in general). However, existing traceback techniques require either the cooperation of external parties or a priori knowledge about the attacker.
We propose BGPeek-a-Boo, a BGP-based approach to trace back amplification attacks to their origin network. BGPeek-a-Boo monitors amplification attacks with honeypots and uses BGP poisoning to temporarily shut down ingress traffic from selected Autonomous Systems. By systematically probing the entire AS space, we detect systems forwarding and originating spoofed traffic. We then show how a graph-based model of BGP route propagation can reduce the search space, resulting in a 5x median speed-up and over 20x for 1/4 of all cases. BGPeek-a-Boo achieves a unique traceback result 60% of the time in a simulation-based evaluation supported by real-world experiments
How Effective are Smart Contract Analysis Tools? Evaluating Smart Contract Static Analysis Tools Using Bug Injection
Security attacks targeting smart contracts have been on the rise, which have
led to financial loss and erosion of trust. Therefore, it is important to
enable developers to discover security vulnerabilities in smart contracts
before deployment. A number of static analysis tools have been developed for
finding security bugs in smart contracts. However, despite the numerous
bug-finding tools, there is no systematic approach to evaluate the proposed
tools and gauge their effectiveness. This paper proposes SolidiFI, an automated
and systematic approach for evaluating smart contract static analysis tools.
SolidiFI is based on injecting bugs (i.e., code defects) into all potential
locations in a smart contract to introduce targeted security vulnerabilities.
SolidiFI then checks the generated buggy contract using the static analysis
tools, and identifies the bugs that the tools are unable to detect
(false-negatives) along with identifying the bugs reported as false-positives.
SolidiFI is used to evaluate six widely-used static analysis tools, namely,
Oyente, Securify, Mythril, SmartCheck, Manticore and Slither, using a set of 50
contracts injected by 9369 distinct bugs. It finds several instances of bugs
that are not detected by the evaluated tools despite their claims of being able
to detect such bugs, and all the tools report many false positivesComment: ISSTA 202
ÆGIS: Smart Shielding of Smart Contracts
In recent years, smart contracts have suffered major exploits, losing millions of dollars. Unlike traditional programs, smart contracts cannot be updated once deployed. Though various tools were pro- posed to detect vulnerable smart contracts, they all fail to protect contracts that have already been deployed on the blockchain. More- over, they focus on vulnerabilities, but do not address scams (e.g., honeypots). In this work, we introduce ÆGIS, a tool that shields smart contracts and users on the blockchain from being exploited. To this end, ÆGIS reverts transactions in real-time based on pat- tern matching. These patterns encode the detection of malicious transactions that trigger exploits or scams. New patterns are voted upon and stored via a smart contract, thus leveraging the benefits of tamper-resistance and transparency provided by blockchain. By allowing its protection to be updated, the smart contract acts as a smart shield
Linking Amplification DDoS Attacks to Booter Services
We present techniques for attributing amplification DDoS
attacks to the booter services that launched the attack. Our k-Nearest
Neighbor (k -NN) classification algorithm is based on features that are
characteristic for a DDoS service, such as the set of reflectors used by that
service. This allows us to attribute DDoS attacks based on observations
from honeypot amplifiers, augmented with training data from ground
truth attack-to-services mappings we generated by subscribing to DDoS
services and attacking ourselves in a controlled environment. Our eval-
uation shows that we can attribute DNS and NTP attacks observed by
the honeypots with a precision of over 99% while still achieving recall
of over 69% in the most challenging real-time attribution scenario. Fur-
thermore, we develop a similarly precise technique that allows a victim
to attribute an attack based on a slightly different set of features that
can be extracted from a victim’s network traces. Executing our k -NN
classifier over all attacks observed by the honeypots shows that 25.53%
(49,297) of the DNS attacks can be attributed to 7 booter services and
13.34% (38,520) of the NTP attacks can be attributed to 15 booter ser-
vices. This demonstrates the potential benefits of DDoS attribution to
identify harmful DDoS services and victims of these services
Efficient Unlinkable Sanitizable Signatures from Signatures with Re-Randomizable Keys
In a sanitizable signature scheme the signer allows a designated third party, called the sanitizer, to modify certain parts of the message and adapt the signature accordingly. Ateniese et al. (ESORICS 2005) introduced this primitive and proposed five security properties which were formalized by Brzuska et al.~(PKC 2009). Subsequently, Brzuska et al. (PKC 2010) suggested an additional security notion, called unlinkability which says that one cannot link sanitized message-signature pairs of the same document. Moreover, the authors gave a generic construction based on group signatures that have a certain structure. However, the special structure required from the group signature scheme only allows for inefficient instantiations.
Here, we present the first efficient instantiation of unlinkable sanitizable signatures. Our construction is based on a novel type of signature schemes with re-randomizable keys. Intuitively, this property allows to re-randomize both the signing and the verification key separately but consistently. This allows us to sign the message with a re-randomized key and to prove in zero-knowledge that the derived key originates from either the signer or the sanitizer. We instantiate this generic idea with Schnorr signatures and efficient -protocols, which we convert into non-interactive zero-knowledge proofs via the Fiat-Shamir transformation. Our construction is at least one order of magnitude faster than instantiating the generic scheme of Brzuska et al. with the most efficient group signature schemes
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