Core Viewpoint - A significant number of users reported unauthorized large transactions on their Shanghai Pudong Development Bank (SPDB) credit cards, particularly in Brazil, raising concerns about potential fraud and security breaches [1][2]. Group 1: Incident Overview - Multiple users have reported unauthorized transactions on their SPDB credit cards occurring around September 9, with many of these users never having visited Brazil [1]. - A group chat on a social platform has formed among affected cardholders, exceeding one hundred members [2]. - SPDB's credit card center announced on September 13 that they had initiated an emergency response with Mastercard to detect and block the risks [2]. Group 2: Customer Experience - Affected cardholders, such as a user named Xiao Pan, reported that they did not receive transaction alerts until days after the unauthorized transactions occurred [2]. - Customer service advised affected users to file police reports and assured them that they would not be liable for fraudulent transactions if confirmed [2]. - SPDB confirmed that the fraud was due to external attacks affecting some Mastercard cardholders and emphasized their commitment to protecting customer rights [2][3]. Group 3: Transaction Details - The unauthorized transactions typically amounted to around 4900 BRL (approximately 6400 RMB), seemingly designed to avoid exceeding 5000 BRL [2]. - The types of merchants involved in these transactions included used car dealerships, restaurants, and taxi services [2]. Group 4: Card Information - The affected credit cards are primarily the "Red Sand" cards issued by SPDB in collaboration with Mastercard, with many users holding the older version designed for overseas use [3]. - The older magnetic stripe cards are considered less secure compared to newer chip cards, which are more resistant to data copying [4]. Group 5: Security Awareness - The China Banking Association has highlighted that card fraud often results from card information being compromised or personal data being leaked [4]. - Consumers are advised to enhance their transaction security awareness and to avoid sharing personal information or lending their cards to others [4].