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Related papers: Making Defeating CAPTCHAs Harder for Bots

200 papers

Adversarial Internet robots (botnets) represent a growing threat to the safe use and stability of the Internet. Botnets can play a role in launching adversary reconnaissance (scanning and phishing), influence operations (upvoting), and…

In recent years, the rapid development of artificial intelligence (AI) especially multi-modal Large Language Models (MLLMs), has enabled it to understand text, images, videos, and other multimedia data, allowing AI systems to execute…

Cryptography and Security · Computer Science 2025-04-02 Lehao Lin , Ke Wang , Maha Abdallah , Wei Cai

Turing test was originally proposed to examine whether machine's behavior is indistinguishable from a human. The most popular and practical Turing test is CAPTCHA, which is to discriminate algorithm from human by offering recognition-alike…

Computer Vision and Pattern Recognition · Computer Science 2019-04-23 Jiaming Zhang , Jitao Sang , Kaiyuan Xu , Shangxi Wu , Yongli Hu , Yanfeng Sun , Jian Yu

Crowdsourcing human-solving or online typing attacks are destructive problems. However, studies into these topics have been limited. In this paper, we focus on this kind of attacks whereby all the CAPTCHAs can be simply broken because of…

Cryptography and Security · Computer Science 2019-04-30 Jianyi Zhang , Xiali Hei , Zhiqiang Wang

Text CAPTCHA has been an effective means to protect online systems from spams and abuses caused by automatic scripts which pretend to be human beings. However, nearly all the Text CAPTCHA designs in nowadays are based on English characters,…

Human-Computer Interaction · Computer Science 2016-12-06 Junnan Yu , Xuna Ma , Ting Han

Nowadays, people generate and share massive content on online platforms (e.g., social networks, blogs). In 2021, the 1.9 billion daily active Facebook users posted around 150 thousand photos every minute. Content moderators constantly…

Cryptography and Security · Computer Science 2022-04-05 Mauro Conti , Luca Pajola , Pier Paolo Tricomi

The arm race between spambots and spambot-detectors is made of several cycles (or generations): a new wave of spambots is created (and new spam is spread), new spambot filters are derived and old spambots mutate (or evolve) to new species.…

Social and Information Networks · Computer Science 2019-04-11 Stefano Cresci , Marinella Petrocchi , Angelo Spognardi , Stefano Tognazzi

As automation bot technology and Artificial Intelligence is evolving rapidly, conventional human verification techniques like voice CAPTCHAs and knowledge-based authentication are becoming less effective. Bots and scrapers with Artificial…

Cryptography and Security · Computer Science 2025-11-12 Aditya Mitra , Sibi Chakkaravarthy Sethuraman , Devi Priya V S

Some protected password change protocols were proposed. However, the previous protocols were easily vulnerable to several attacks such as denial of service, password guessing, stolen-verifier and impersonation atacks etc. Recently, Chang et…

Cryptography and Security · Computer Science 2007-05-23 Ren-Chiun Wang , Chou-Chen Yang , Kun-Ru Mo

As technology and gadgets continue to evolve, the need for bot-friendly and user-friendly internet becomes increasingly critical. This work discusses a methodology for implementation and feasibility of replacing traditional CAPTCHA…

Cryptography and Security · Computer Science 2024-03-05 Sujanavan Tiruvayipati

System passwords serve as critical credentials for user authentication and access control when logging into operating systems or applications. Upon entering a valid password, users pass verification to access system resources and execute…

Cryptography and Security · Computer Science 2026-02-03 Chaofang Shi , Zhongwen Li , Xiaoqi Li

With the rapid development of internet technologies, social networks, and other related areas, user authentication becomes more and more important to protect the data of users. Password authentication is one of the widely used methods to…

Cryptography and Security · Computer Science 2023-01-31 Lifeng Han

Sophisticated attackers find bugs in software, evaluate their exploitability, and then create and launch exploits for bugs found to be exploitable. Most efforts to secure software attempt either to eliminate bugs or to add mitigations that…

Cryptography and Security · Computer Science 2018-08-03 Zhenghao Hu , Yu Hu , Brendan Dolan-Gavitt

This paper studies how multimodal large language models (MLLMs) undermine the security guarantees of visual CAPTCHA. We identify the attack surface where an adversary can cheaply automate CAPTCHA solving using off-the-shelf models. We…

Cryptography and Security · Computer Science 2026-05-13 Junyu Wang , Changjia Zhu , Yuanbo Zhou , Lingyao Li , Xu He , Mingkui Wei , Junjie Xiong

Bots constitute a significant portion of Internet traffic and are a source of various issues across multiple domains. Modern bots often become indistinguishable from real users, as they employ similar methods to browse the web, including…

Machine Learning · Computer Science 2024-12-04 Jan Kadel , August See , Ritwik Sinha , Mathias Fischer

Even though passwords are the most convenient means of authentication, they bring along themselves the threat of dictionary attacks. Dictionary attacks may be of two kinds: online and offline. While offline dictionary attacks are possible…

Cryptography and Security · Computer Science 2011-11-17 Vipul Goyal , Virendra Kumar , Mayank Singh , Ajith Abraham , Sugata Sanyal

Phishing attacks have become the most used technique in the online scams, initiating more than 91% of cyberattacks, from 2012 onwards. This study reviews how Phishing and Spear Phishing attacks are carried out by the phishers, through 5…

Cryptography and Security · Computer Science 2020-06-02 Alessandro Ecclesie Agazzi

As more business activities are being automated and an increasing number of computers are being used to store vital and sensitive information the need for secure computer systems becomes more apparent. These systems can be achieved only…

Computers and Society · Computer Science 2009-09-25 Shireesh Reddy Annam

The obstacles of each security system combined with the increase of cyber-attacks, negatively affect the effectiveness of network security management and rise the activities to be taken by the security staff and network administrators. So,…

Cryptography and Security · Computer Science 2025-02-06 Mamoon A. Al Jbaar , Adel Jalal Yousif , Qutaiba I. Ali

To enhance the security of text CAPTCHAs, various methods have been employed, such as adding the interference lines on the text, randomly distorting the characters, and overlapping multiple characters. These methods partly increase the…

Cryptography and Security · Computer Science 2023-08-17 Ran Jiang , Sanfeng Zhang , Linfeng Liu , Yanbing Peng