Bixby as a Backdoor: How Two Researchers Chained Samsung's Own Apps Into a Full Device Takeover
A pair of security researchers turned Samsung's own preloaded software against itself, chaining together multiple vulnerabilities to achieve full system-level access on Galaxy smartphones. The work earned them $50,000 at Pwn2Own Ireland in October 2025, and they've now walked through the full technical breakdown at Black Hat.
The researchers are Dimitrios Valsamaras, a senior security researcher at Microsoft, and Ken Gannon, head of mobile research at Mobile Hacking Lab. Their target: a Samsung Galaxy S25. Their toolkit: entirely Samsung's own apps.
The attack begins with something mundane. A malicious link, served through an ad or a messaging app, nudges the victim into a single click. From there, the chain unfolds.
That click triggers CVE-2025-21079, which forces Samsung Members, the preloaded support and diagnostics app found on most mid-range and flagship Galaxy devices, to connect to a site the attacker controls. From there, the malicious site pushes Samsung Members into opening Samsung Account, the app that ties users into Samsung's broader ecosystem.
Once inside Samsung Account, a second vulnerability (CVE-2025-58486) redirects it to another attacker-controlled server. That server then exploits a cross-site scripting flaw, CVE-2025-58487, to coerce Samsung Account into opening Bixby. This works because Samsung Account holds a specific permission that grants it access to a side entrance in Bixby's architecture, one that isn't exposed to ordinary apps. As Gannon put it: "Think of it as a 'side entrance' and Samsung Account happens to be a key holder."
Getting into Bixby is only half the story. The researchers then turned their attention to Capsules, the hidden background services that apps use to respond to Bixby voice commands. When you ask Bixby to do something, it doesn't act directly; it routes the request through a Capsule specific to the app in question. Samsung locks down Capsule access so that only Bixby itself can communicate with them. Sensible, in theory.
In practice, Gannon and Valsamaras reverse-engineered the Capsule infrastructure and found a way to weaponise it. By forcing Bixby to invoke Capsules on their behalf, they could pull sensitive data from the device and escalate to system-level permissions, the highest privilege tier achievable on a standard consumer Android device without physically modifying it.
From there, remote code execution followed. Full device control, achieved through a single link click and a chain of Samsung's own trusted software.
The exploit was confirmed to work across Samsung Galaxy S25, S24, and Flip 7 handsets. Older Samsung devices that haven't received patches remain vulnerable.
Samsung moved fairly quickly once the competition concluded. Patches for Samsung Members landed in November 2025, cutting off the initial entry point. The Samsung Account flaws were addressed in December. Whether those patches have reached all affected devices is a different question, particularly for older models or budget handsets where some of the targeted apps may not be preinstalled at all.
Samsung didn't respond when asked for comment.
The research is a solid reminder that the attack surface on modern smartphones isn't just third-party apps or dodgy links. Sometimes the biggest risk is everything the manufacturer ships by default.