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Why Johnny Can't Encrypt: A Usability Evaluation of PGP 5.0 (1999)
Seminal 1999 USENIX study finds most novice users cannot correctly sign and encrypt email with PGP 5.0 in 90 minutes.
Whitten and Tygar's USENIX Security Symposium paper evaluates whether cryptography novices can use PGP 5.0 effectively, using cognitive walkthrough analysis and a laboratory user test. The majority of test participants failed to successfully sign and encrypt a message within 90 minutes, despite PGP 5.0 having a well-regarded graphical interface. The authors argue that security requires usability standards beyond those of general consumer software and propose domain-specific UI design principles for security. The paper is a foundational reference in usable security research.
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Zombie Card Attack Can Revive Expired Visa Cards for Contactless Payments
UMass Amherst researchers demonstrate Zombie Card, an NFC relay attack that revives expired Visa contactless cards for in-store purchases without breaking cryptography.
Researchers at the University of Massachusetts Amherst presented the Zombie Card attack at USENIX Security 2026, showing that Visa's Kernel 3 does not cryptographically bind the Application Expiration Date (tag 5F24) the terminal reads with the Track 2 expiry seen by the issuer. By positioning an NFC man-in-the-middle relay, an attacker can rewrite the terminal-facing expiration date of an expired card and complete contactless purchases, provided the account remains open under the same PAN and the bank does not independently re-check expiry. Testing across five major US banks found three distinct policies; Visa Kernel 3 accepted the modified date, while Mastercard, American Express, and Discover kernels declined modified transactions. Findings were disclosed to Visa and affected banks in May 2025, no CVE has been assigned, and no exploitation has been reported.
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Researchers find a loophole that lets expired credit cards make unauthorized payments
UMass Amherst researchers showed at USENIX Security 2026 that NFC relay attacks can rewrite unprotected expiration dates, letting expired Visa contactless cards keep making payments.
UMass Amherst researchers presented the Zombie Card attack at USENIX Security 2026, using two smartphones to relay and modify NFC payment data from expired Visa cards. The expiration date lies outside the card's digital signature coverage in Visa Kernel 3, and one major US bank accepted $1-$500 test purchases plus live $2.79 and $3.19 purchases with rewritten dates. Mastercard, American Express, and Discover rejected tampered dates; researchers notified Visa in May 2025 and no CVE or confirmed fix existed at publication.
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Are Unreachable Nodes Truly Safe? Fully Eclipsing Monero's P2P Network!
Researchers present Nyx and Moros, the first eclipse attacks against Monero nodes behind NATs, requiring no inbound access and demonstrated on mainnet.
The paper presents the first eclipse attacks tailored to unreachable Monero nodes operating behind NATs, requiring no inbound access to the victim. The attacks poison the peerlists of reachable nodes, which relay contamination to unreachable nodes' whitelists, then exploit Monero's outbound connection refresh logic to evict benign neighbors and monopolize all outbound connections. Nyx achieves a complete, persistent eclipse of long-running unreachable nodes in large-scale SEED Emulator simulations, while Moros stealthily eclipses newly joined nodes during bootstrapping and was demonstrated on the Monero mainnet. Countermeasures are proposed.
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China's AI-Enabled APT Operations Are Getting Interesting
Bitdefender links seven RAT families, five previously undocumented, to China-nexus espionage actor SilkParasite using AI-assisted malware development against Central Asian governments.
A Bitdefender report attributes seven remote access tool families to a single actor dubbed SilkParasite, with medium confidence a China-nexus group targeting governments in Uzbekistan, Turkmenistan and Kazakhstan. The RATs are written in .NET, C++, Go and JavaScript, use C2 via Google Drive and protocols like HTTP, DNS and TCP, and employ modular plugin architectures with regular rotation of infrastructure, encryption material and persistence artifacts. Evidence of AI-assisted development includes leftover test functions, placeholder encryption keys, and GoginRAT and NomadRAT sharing a high-level architecture despite different languages, suggesting a specification implemented twice with AI. The newsletter also covers the US Operation Economic Outcast sanctioning six MOIS-linked Iranian hackers, including hands-on-keyboard operators who targeted US critical infrastructure.
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Week in review: Records allegedly stolen from Azure tenants, Medusa ransomware hits 500+ orgs
Week in review: Medusa ransomware hit 500+ orgs per CISA, millions of Azure tenant records allegedly stolen, SafePal and French tax authority breaches disclosed.
Help Net Security's weekly roundup covers the FBI, CISA, and HHS joint advisory update reporting Medusa ransomware has breached more than 500 organizations since June 2021, and threat actor TheHatman's claim of millions of employee records stolen from Azure tenants of Fortune 500 firms including McDonald's, Vodafone, Kyndryl, and Tata Consultancy Services, per Hudson Rock. It also covers the SafePal breach affecting 39,798 customers, France's DGFiP breach exposing data on 678,000 individuals, and UT San delaying its fall semester after a cyberattack. Security items include critical unauthenticated GitLab flaw CVE-2026-19478, an actively exploited patched macOS Screen Sharing flaw deploying a cryptominer, US charges against 17 Mabna Institute Iranian hackers over 31TB of stolen academic data, and Google Mandiant's AI agents finding 100+ high-severity vulnerabilities.
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Your Shredded Visa Card May Still Work at the Checkout
UMass Amherst researchers demonstrated expired Visa contactless cards can complete real purchases via relay attacks exploiting Visa Kernel 3's unsigned expiry date handling.
University of Massachusetts Amherst researchers presented at USENIX Security 2026 that expired Visa contactless cards can be revived for real purchases through an NFC man-in-the-middle attack on Visa's Kernel 3. The attack alters the expiry date the terminal sees (tag 5F24) while leaving the Track 2 Equivalent Data (tag 57) sent to the issuing bank unchanged, and the card's cryptographic signature does not cover the expiry date. Two Android phones emulating card and terminal relayed transactions within Visa's 500-millisecond limit. Mastercard, American Express, and Discover kernels blocked the attack, while Visa Kernel 3 did not; researchers also modified the Consumer Device Cardholder Verification Method flag at five US banks, and attackers can also exploit Terminal Verification Results zero-filling. Visa was notified in May 2025 and December 2025; no CVE has been assigned.
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Risky Bulletin: Academics find source code overlaps between Geedge and China's Great Firewall
Academics linked Chinese vendor Geedge Networks' Tiangou Secure Gateway source code to one of the Great Firewall's three traffic filtering capabilities.
US researchers presenting at USENIX Security reconstructed Geedge Networks' Tiangou Secure Gateway firmware from over 100,000 leaked files, including Git repositories with commit history, and matched its filtering behavior to sections of China's Great Firewall. They found only 1 of 3 characterized DNS injectors matched Geedge code, noted the system relies on memory-unsafe C components and copied third-party code, and said its bugs could aid future circumvention tools. Geedge also exports censorship tools to Kazakhstan, Ethiopia, Pakistan, and Myanmar. The newsletter additionally rounds up multiple breaches.
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New Cryptographic Context Injection Attack Could Let Web Pages Steal Grok Chat Data
Adversa AI demonstrated 'Cryptographic Context Injection' making xAI's Grok leak chat history and session data to attacker-controlled servers via encrypted web payloads.
Adversa AI disclosed a technique where a web page carries an encrypted JSON object (PBKDF2 and AES-256-GCM) that Grok's code-execution runtime decrypts, letting attacker instructions bypass content classifiers and reach the model's context. The decrypted instructions direct Grok to embed the user's name, approximate location, subscription tier and ongoing conversation into a URL it fetches, exfiltrating the data without confirmation. Testing targeted grok.com running Grok 4.5 Fast on August 19, 2026, with a reported 40% success rate over 20 attempts since June; no CVE, patch, or in-the-wild exploitation is reported. A related demonstration reproduced Gemini 3 Flash system instructions via a fabricated Python traceback, while GPT-5 failed to parse the payload and Claude Sonnet 4.5 flagged it as prompt injection.
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SafePal Hardware Wallet Maker Says Flaw Exposed Data of Nearly 40,000 Customers
SafePal disclosed an order-tracking plug-in authorization flaw exposing names, emails, addresses and purchase details of 39,798 hardware wallet customers; no wallet credentials affected.
Hardware wallet maker SafePal disclosed that an authorization flaw in an order-tracking plug-in exposed names, email addresses, shipping addresses, phone numbers and purchase details of approximately 39,798 customers. No seed phrases, private keys, wallet credentials or financial information were exposed, and SafePal found no evidence of wallet or fund compromise. A separate configuration error left a data-cleanup process broken between September 2025 and April 2026, extending the affected order window back to March 2025. A threat actor has advertised a matching dataset on a cybercrime forum, and the company has fixed the flaw, cut data retention to 90 days, purged affected records, engaged third-party validators and taken down over 30 phishing sites.
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PentestGPT: Open-source automated penetration testing agentic framework
Open-source PentestGPT runs autonomous LLM-driven penetration tests via Claude Code and Codex, with legacy human-in-the-loop mode supporting many providers.
PentestGPT, originally published at USENIX Security 2024 by Gelei Deng and colleagues, is an open-source framework that lets a large language model autonomously run penetration testing stages (recon, exploit, walkthrough) with no human in the loop, driving Claude Code or Codex CLIs. A legacy interactive mode uses three cooperating LLM sessions maintaining a Pentesting Task Tree and supports OpenAI, Anthropic, Google Gemini, DeepSeek, xAI, Qwen, Moonshot, and local models via Ollama. The tool sends anonymous telemetry to Langfuse by default, excluding command outputs, credentials, and flags, and is available free on GitHub.
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A Malicious SIM Card Can Run Attacker Code Inside the Modems Behind Cellular IoT Devices
Researchers showed malicious SIM cards can issue RUN AT commands to execute code on Qualcomm modems, compromising Quectel-based cellular IoT devices like EV chargers.
Researchers at the University of Birmingham and Fuzzware found 9 of 26 tested devices accept SIM proactive commands, including six Qualcomm-based cellular modules, five of them Quectel. They achieved code execution on a commercial Autel EV charger via the Quectel EC25's atfwd_daemon unsafe format string, and demonstrated an irreversible 2G downgrade, modem power-off, and arbitrary file reads via a root TFTP daemon on a Quectel EG25-G. Attacks require a hostile SIM already in the slot or an interposer; no attacks have been reported in the wild. Qualcomm has built a hardened configuration disabling the interface by default and Quectel mitigated the file-access flaw; the paper was presented at USENIX WOOT.
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