Incident Overview
On July 23, 2026, Bitcoin Layer-2 protocol B² Network suffered a security incident on BNB Chain targeting its B2 token staking service, resulting in the unauthorized extraction of approximately 8.59 million B2 tokens (valued at ~$3.86 million).
The exploit was caused by a compromise of the administrative upgrade authority governing the upgradeable proxy contract for B² Network's staking service. An address (0x35fE...b287d) that had granted itself privileged admin permissions over a year prior (May 2025) executed an upgradeToAndCall function call on the live staking proxy contract. This replaced the legitimate contract implementation with a malicious logic contract (0x0B875E...C9DCa).
Six minutes after the proxy upgrade, the attacker invoked draining functions through the newly deployed logic, extracting ~8.59 million B2 tokens across nine batch calls within 45 minutes. The stolen B2 tokens were swapped on-chain for 5,409 WBNB, converted to 1,128 ETH, and bridged out of BNB Chain via Near Intents.
Malicious Implementation Contract: 0x0B875E23…cC9DCa
Upgrade Transaction: 0x2069714b…47d769
Incident Report
Protocol Information
Market Context at Time of Hack
What the Attacker Needed to Succeed
Understanding the prerequisites for this type of attack helps auditors identify protocols that are most at risk and helps developers build better defenses.
What Auditors Should Check
If you're auditing a protocol with similar architecture to B² Network, these are the critical security checks that could have prevented this incident (July 2026).
- Verify all logic paths related to Access Control are guarded by proper access controls and input validation - see the Access Control Attacks attack class for patterns
- Review privileged functions (owner, admin, governance) for potential abuse vectors - centralization risks should be documented and bounded with timelocks or multi-sigs
Master these auditing techniques with hands-on labs and real exploit scenarios in the Smart Contract Hacking course.
Free TrialSecurity Audit History
- Audit Report 1 Report
Related Attack Classes
The technique used in this hack maps to these vulnerability classes in our security curriculum:
Sources & References
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