How much was lost in the Bitomat hack?

The Bitomat hack resulted in $236K in losses on July 26, 2011.

What attack technique was used in the Bitomat exploit?

The Bitomat exploit utilized Access Control. Understanding this attack vector is critical for smart contract auditors and developers building secure DeFi protocols.

How can developers prevent similar smart contract attacks?

Preventing smart contract hacks requires a combination of secure coding practices, thorough security audits, and understanding common attack vectors like reentrancy, oracle manipulation, and access control flaws. Smart Contract Hacking (SCH) provides hands-on training to help developers and auditors identify and prevent vulnerabilities before deployment.

Bitomat Hack

TOTAL LOST $236K

Low Jul 26, 2011 Access Control

Affected Chain 2011 Incident surface

Recovered - No recovery reported

All-Time Rank #1214 By amount stolen

Protocol Type CEX Target category

Incident Overview

Bitomat, Poland-based third largest Bitcoin exchange, announced that as of July 26 they lost access to their wallet.dat file and thus the exchange’s entire fund base has become inaccessible.

According to the statement published by Bitomat, it appears that they were using Amazon Web Service’s Elastic Cloud Computing network and held all of their information, including the wallet file for the exchanges bitcoins in a virtual machine.

"On 26 July 2011 at about 11:00 PM, I noticed that bitcoin server was out of resources and I had to increase RAM. As a result of this operation, the virtual machine was deleted and all data lost, including bitcoin wallet and its backups.

I have established that data was lost because settings of the virtual machine were changed, although I didn’t change them myself. Amazon Web Services Company, which hosts our servers, says that the cleared machine has been set up to be irretrievably destroyed (including the data on the disks) at the shutdown.

I’m still trying to establish who has changed the settings and whether I will be able to recover the lost data. Unfortunately cooperation with Amazon Web Services is very difficult. As soon as I realized that my virtual machine was lost I have ordered AWS premium support, talked to the manager and asked for securing of the disk data. So far, without success." - was said in the statement.

This is classified as a Access Control Attacks . Compare similar hacks →

Incident Report

Protocol / Project Bitomat

Date of Incident July 26, 2011

Attack Technique Access Control

Classification CeFi

Primary Source View Post-Mortem

Protocol Information

Protocol Type CEX

Official Website bitomato.com/

Protocol Twitter/X @Bitomato_ex

Team Anonymous

Source Code Unverified

Market Context at Time of Hack

Token Categories

Memes Solana Ecosystem Pump Fun Ecosystem

Protocol Links

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.

Technical Knowledge Operational-security tradecraft (phishing, malware, leaked seed phrases, or insider access) to obtain treasury signing authority

Capital Required Minimal capital - only enough to cover gas while draining the compromised accounts

On-Chain Access Valid signing authority over the compromised wallets / multisig signers, allowing direct transfer of funds or stake authorization

Target Reconnaissance Identification of Bitomat's high-value treasury accounts and the authority / multisig structure controlling them

Execution Speed Speed to drain the compromised accounts before the team detects the breach and revokes signing authority or freezes the assets

Obfuscation Plan A strategy to launder and move stolen funds - typically through mixers, cross-chain bridges, or decentralized DEX swaps to resist tracing

What Auditors Should Check

Could this have been caught in audit? Likely — with a thorough Access Control audit checklist and test coverage

If you're auditing a protocol with similar architecture to Bitomat, these are the critical security checks that could have prevented this incident (July 2011).

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.

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Related Attack Classes

The technique used in this hack maps to these vulnerability classes in our security curriculum:

See all Access Control Attacks examples →

Access Control Attacks

Sources & References

01
Source 1 https://siliconangle.com/2011/08/01/third-largest-bitcoin-exchan…

Threat Assessment

Severity Level

LOW

Attack Vector Access Control
Root Cause CeFi
Year 2011

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