arXiv subjects

Philipp Markert

Publications and source records attributed to Philipp Markert.

5 recordsLinked to original sources

arXiv2023

A Transcontinental Analysis of Account Remediation Protocols of Popular Websites

Websites are used regularly in our day-today lives, yet research has shown that it is challenging for many users to use them securely, e.g., most prominently due to weak passwords through which they access their accounts. At the same time, many services employ low-security measures, making their users even more prone to account compromises with little to no means of remediating compromised accounts. Additionally, remediating compromised accounts requires users to complete a series of steps, ideally all provided and explained by the service. However, for U.S.-based websites, prior research has shown that the advice provided by many services is often incomplete. To further understand the underlying issue and its implications, this paper reports on a study that analyzes the account remediation procedure covering the 50 most popular websites in 30 countries, 6 each in Africa, the Americas, Asia, Europe, and Oceania. We conducted the first transcontinental analysis on the account remediation protocols of popular websites. The analysis is based on 5 steps websites need to provide advice for: compromise discovery, account recovery, access limitation, service restoration, and prevention. We find that the lack of advice prior work identified for websites from the U.S. also holds across continents, with the presence ranging from 37% to 77% on average. Additionally, we identified considerable differences when comparing countries and continents, with countries in Africa and Oceania significantly more affected by the lack of advice. To address this, we suggest providing publicly available and easy-to-follow remediation advice for users and guidance for website providers so they can provide all the necessary information.

cs.CR↗

arXiv2022

Understanding Users' Interaction with Login Notifications

Login notifications intend to inform users about sign-ins and help them protect their accounts from unauthorized access. Notifications are usually sent if a login deviates from previous ones, potentially indicating malicious activity. They contain information like the location, date, time, and device used to sign in. Users are challenged to verify whether they recognize the login (because it was them or someone they know) or to protect their account from unwanted access. In a user study, we explore users' comprehension, reactions, and expectations of login notifications. We utilize two treatments to measure users' behavior in response to notifications sent for a login they initiated or based on a malicious actor relying on statistical sign-in information. We find that users identify legitimate logins but need more support to halt malicious sign-ins. We discuss the identified problems and give recommendations for service providers to ensure usable and secure logins for everyone.

cs.HC↗

arXiv2021

"I have no idea what they're trying to accomplish:" Enthusiastic and Casual Signal Users' Understanding of Signal PINs

We conducted an online study with $n = 235$ Signal users on their understanding and usage of PINs in Signal. In our study, we observe a split in PIN management and composition strategies between users who can explain the purpose of the Signal PINs (56%; enthusiasts) and users who cannot (44%; casual users). Encouraging adoption of PINs by Signal appears quite successful: only 14% opted-out of setting a PIN entirely. Among those who did set a PIN, most enthusiasts had long, complex alphanumeric PINs generated by and saved in a password manager. Meanwhile more casual Signal users mostly relied on short numeric-only PINs. Our results suggest that better communication about the purpose of the Signal PIN could help more casual users understand the features PINs enable (such as that it is not simply a personal identification number). This communication could encourage a stronger security posture.

cs.CR↗

arXiv2020

Knock, Knock. Who's There? On the Security of LG's Knock Codes

Knock Codes are a knowledge-based unlock authentication scheme used on LG smartphones where a user enters a code by tapping or "knocking" a sequence on a 2x2 grid. While a lesser used authentication method, as compared to PINs or Android patterns, there is likely a large number of Knock Code users; we estimate, 700,000--2,500,000 in the US alone. In this paper, we studied Knock Codes security asking participants to select codes on mobile devices in three settings: a control treatment, a blocklist treatment, and a treatment with a larger, 2x3 grid. We find that Knock Codes are significantly weaker than other deployed authentication, e.g., PINs or Android patterns. In a simulated attacker setting, 2x3 grids offered no additional security, but blocklisting was more beneficial, making Knock Codes' security similar to Android patterns. Participants expressed positive perceptions of Knock Codes, but usability was challenged. SUS values were "marginal" or "ok" across treatments. Based on these findings, we recommend deploying blacklists for selecting a Knock Code because it improves security but has limited impact on usability perceptions.

cs.CR↗

arXiv2020

This PIN Can Be Easily Guessed: Analyzing the Security of Smartphone Unlock PINs

In this paper, we provide the first comprehensive study of user-chosen 4- and 6-digit PINs (n=1220) collected on smartphones with participants being explicitly primed for device unlocking. We find that against a throttled attacker (with 10, 30, or 100 guesses, matching the smartphone unlock setting), using 6-digit PINs instead of 4-digit PINs provides little to no increase in security, and surprisingly may even decrease security. We also study the effects of blocklists, where a set of "easy to guess" PINs is disallowed during selection. Two such blocklists are in use today by iOS, for 4-digits (274 PINs) as well as 6-digits (2910 PINs). We extracted both blocklists compared them with four other blocklists, including a small 4-digit (27 PINs), a large 4-digit (2740 PINs), and two placebo blocklists for 4- and 6-digit PINs that always excluded the first-choice PIN. We find that relatively small blocklists in use today by iOS offer little or no benefit against a throttled guessing attack. Security gains are only observed when the blocklists are much larger, which in turn comes at the cost of increased user frustration. Our analysis suggests that a blocklist at about 10% of the PIN space may provide the best balance between usability and security.

cs.CR↗