- Fake AI sidebars can perfectly mimic real ones to steal secrets, experts warn
- Malicious extensions only need minimal permissions to cause maximum chaos
- AI browsers risk turning useful automation into conduits for silent data theft
New “agent” browsers that offer an AI-powered sidebar promise some convenience but can widen the window for deceptive attacks, experts have warned.
Researchers at browser security firm SquareX have discovered that an innocuous-looking extension can overlay a fake sidebar on the browsing surface, intercepting inputs and returning malicious instructions that appear legitimate.
This technique undermines the implicit trust users place in in-browser wizards and makes detection difficult because the overlay mimics standard interaction flows.
How identity theft works in practice
The attack uses extension features to inject JavaScript into web pages, creating a fake sidebar above the real interface and capturing user actions.
Reported scenarios include directing users to phishing sites and capturing OAuth tokens via fake file sharing prompts. It also recommends commands that install remote access backdoors on victims’ devices.
The consequences quickly escalate when these instructions involve account credentials or automated workflows.
Many extensions request broad permissions, such as host access and storage, that are typically granted to productivity tools, reducing the value of permission scanning as a detection method.
Conventional antivirus suites and browser permission models were not designed to recognize a deceptive overlay that never modifies the browser code itself.
As more vendors integrate sidebars into major browser families, the collective attack surface expands and becomes more difficult to secure.
Users should consider in-browser AI assistants as experimental features and avoid handling sensitive data or allowing account links through them, as this can significantly increase the risk of compromise.
Security teams should strengthen extension governance, implement tighter endpoint controls, and monitor anomalous OAuth activity to reduce risk.
The threat is also directly linked to identity theft when fraudulent interfaces collect credentials and session tokens with convincing accuracy.
Agent browsers introduce new conveniences while creating new vectors for social engineering and technical abuse.
Therefore, vendors should create interface integrity checks, improve extension verification, and provide clearer guidance on their acceptable use.
Until these metrics are widely established and audited, users and organizations should remain skeptical about trusting sidebar agents for any tasks involving sensitive accounts.
Security teams and vendors should prioritize practical mitigation measures, including mandatory code audits for sidebar components and transparent update logs that users and administrators can review regularly.
Via BeepComputer
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