Repackaging is the modification of a legitimate app and its redistribution as a tampered version. In Android ecosystems, an attacker may unpack an APK, patch its code, add malicious logic, then resign and publish it under a lookalike brand or through deceptive channels. The result can appear authentic to a user while behaving very differently from the original software.
This technique matters because it turns the app itself into part of the attack. Any security checks embedded in the binary can be edited out, weakened, or bypassed before the app ever reaches the victim. Repackaging is common in banking trojans, credential theft, and ad fraud, where attackers want to inherit user trust from a real app. Defenses focus on server-side verification, app integrity checks, code signing validation, and runtime attestation, so trust does not depend only on code running on the device.