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SUMMARY:My other ClassLoader is your ClassLoader: Creating evil twin insta
 nces of a class - Dimitrios Valsamaras
DTSTART;TZID=Europe/Luxembourg:20251023T111500
DTEND;TZID=Europe/Luxembourg:20251023T114500
DTSTAMP:20260819T140255Z
UID:pretalx-hack-lu-2025-CHMH78@pretalx.com
DESCRIPTION:The class loader is a fundamental component of the Java Virtua
 l Machine\, responsible for dynamically loading classes into an applicatio
 n's memory during runtime. The functionality of class loaders is outlined 
 by the abstract ClassLoader class\, with the PathClassLoader and DexClassL
 oader being some common implementations in the Android OS.\n\nIn the conte
 xt of data transfer and object management\, dynamic class loading becomes 
 particularly relevant when dealing with Serializable and Parcelable object
 s\, as the ClassLoader implementation plays a crucial role in reconstructi
 ng them. However\, while the Android security model enforces isolation amo
 ng running processes\, nothing prevents an application from creating and m
 aliciously using objects of another app. In fact\, the practice of storing
  application resources and their code in world-readable directories\, ease
 s this process\, since it allows any app to "borrow" the context of anothe
 r and create class loader instances that can be used to construct Java obj
 ects with potentially unsafe content.\n\nAndroid developers often overlook
  this contingency\, placing undue trust to Java objects received from untr
 usted sources. In a typical scenario\, an application handles such objects
 \, without proper caution regarding their encapsulated data. Depending on 
 the use of this data\, such an oversight can lead to unpredicted behavior 
 and under some circumstances\, it can have serious security implications.\
 n\nIn this study\, we demonstrate techniques and explore how third-party a
 pplications\, without requiring any permission\, can leverage the outlined
  behavior to craft and dispatch parcelable Java objects with malicious con
 tent\, to other applications. We further illustrate\, using practical exam
 ples\, the severe security implications that this may have\, underscoring 
 the necessity for more vigilant and comprehensive security practices in An
 droid application development.
LOCATION:Europe
URL:https://pretalx.com/hack-lu-2025/talk/CHMH78/
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