Cybersecurity researchers devised two attack techniques to disrupt the operations of cryptocurrency mining botnets.
Akamai Researchers uncovered two novel techniques to disrupt cryptocurrency mining botnets by exploiting flaws in common mining topologies.
Current methods to stop cryptocurrecy mining botnets are pool bans or infrastructure takedowns, however, both are slow and complex. Researchers developed two faster techniques exploiting vulnerabilities in the stratum protocol to disrupt operations by targeting proxies or wallets, potentially forcing attackers to abandon campaigns.
“We developed two techniques by leveraging the mining topologies and pool policies that enable us to reduce a cryptominer botnet’s effectiveness to the point of completely shutting it down, which forces the attacker to make radical changes to their infrastructure or even abandon the entire campaign.” reads the report published by Akamai.
Researchers developed XMRogue, a tool to disrupt cryptomining botnets using mining proxies. XMRogue allows researchers to impersonate a miner, connect to a mining proxy, submit consecutive bad shares (invalid mining job results), and potentially ban the mining proxy from the pool.
“When mining using a proxy, all the victims are connected to a single server, which means that interfering with the proxy can bring the entire mining operation down.” continues the report. “The idea is simple: By connecting to a malicious proxy as a miner, we can submit invalid mining job results — bad shares — that will bypass the proxy validation and will be submitted to the pool. Consecutive bad shares will eventually get the proxy banned, effectively halting mining operations for the entire cryptomining botnet.”
By sending crafted invalid shares (bad hashes) through Stratum to malicious proxies, they trigger pool-level bans, halting the attacker’s operation. XMRogue bypasses proxy validations by correctly formatting share fields.
In tests conducted by Akamai, it reduced one campaign’s annual revenue from $50K to $12K, a 76% drop, by banning proxies, potentially forcing attackers to abandon the campaign.
Akamai’s second method targets miners connected directly to public pools without proxies. By flooding the pool with over 1,000 login attempts using the attacker’s wallet, the wallet gets temporarily banned for an hour. Though not permanent, this disruption can significantly hinder the attack. The researchers demonstrated the technique targeting Monero miners, however, it is adaptable to other cryptocurrencies.
“When we inspected the mining pool’s source code, another option came to mind — targeting the wallet address. While the previous bad shares policy targeted miner IP addresses, we identified an additional policy that is enforced on the wallet level — the pool will ban the wallet’s address for one hour if it has more than 1,000 workers.” continues the report. “When using proxy mining, an attacker can embed their wallet address exclusively on the proxy server, enabling them to effectively masquerade it. But in situations where direct mining is performed, the wallet address must be present on the victim machine, which enables us to extract it. Getting the attacker banned in this case is straightforward — we just send more than 1,000 login requests using the attacker’s wallet simultaneously, which will force the pool to ban the attacker’s wallet.”
The researchers implemented this second attack technique in the XMRogue tool
The techniques above demonstrate how defenders can disrupt malicious cryptominer campaigns by exploiting mining pool policies, without affecting legitimate miners. While a legitimate user can quickly recover by changing their IP or wallet, attackers face a much bigger challenge. Shutting down a malicious campaign would require changes across the entire botnet, making this defense especially effective against less sophisticated operations.
“We believe that the threat of cryptominers will continue to grow over time. But now we can fight back and disrupt the attacker’s operation, making it much more challenging to monetize cryptominers effectively” concludes the report.
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