Botnet Exploits 13,000 MikroTik Devices By Abusing Misconfigured DNS Records

Cybersecurity experts at Infoblox Threat Intel have uncovered a sophisticated botnet leveraging misconfigured DNS records to bypass email protection systems and deliver malware through spam campaigns.

This botnet, comprising approximately 13,000 compromised MikroTik routers, represents a significant and persistent threat to global cybersecurity.

How the Botnet Operates

The botnet uses a global network of MikroTik routers, many of which have been compromised due to critical vulnerabilities, some stemming from outdated firmware or misconfigured security settings.

The malicious actors behind the operation have exploited these vulnerabilities to install scripts that enable compromised devices as SOCKS proxies tools that obscure the origin of malicious traffic, making it harder to identify the perpetrators.

According to the Infoblox report, the campaign has also capitalized on DNS misconfigurations, focusing particularly on Sender Policy Framework (SPF) records.

SPF records are designed to verify authorized email senders for a domain, but misconfigurations allowed attackers to spoof legitimate sender domains, bypassing protections such as DKIM and DMARC.

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The Malspam Campaign

The malicious actors launched their campaign by impersonating DHL, sending fraudulent emails related to shipping invoices.

emails, bearing subject lines like “Invoice 728” or “Tracking 432,” included ZIP file attachments containing JavaScript malware.

Once downloaded, the malware executed a PowerShell script to contact a command-and-control (C2) server linked to prior suspicious activity out of Russia.

Infoblox’s analysis revealed that the malspam campaign spanned 20,000 sender domains, all taking advantage of misconfigured SPF records that permitted unauthorized servers to send spoofed emails.

With a network of 13,000 compromised MikroTik devices, the botnet is capable of executing a range of cyberattacks, including:

• Distributed Denial-of-Service (DDoS) Attacks: Overwhelming servers with traffic to disrupt services.
• Phishing and Spam: Launching large-scale email campaigns to spread malware or steal credentials.
• Data Theft: Exfiltrating sensitive information for resale or further exploitation.
• Cryptojacking: Hijacking device processing power to mine cryptocurrency.
• Proxy Operations: Acting as a SOCKS4 relay to amplify the scale of cyberattacks and mask the origin of malicious traffic.

DNS Misconfigurations: A Critical Vulnerability

The campaign highlights the dangers of improperly configured DNS records. In many cases, domains were using the “+all” option in their SPF records, which effectively allows any server to send emails on behalf of the domain.

This undermines the purpose of SPF protections, leaving domains vulnerable to spoofing.

Cybersecurity experts emphasize the need for proactive measures to safeguard systems:

1. Audit DNS Settings: Ensure SPF, DKIM, and DMARC configurations are properly implemented. For SPF, use “-all” to restrict unauthorized senders.
2. Update Firmware: Regularly update router firmware to patch vulnerabilities. Disable default admin accounts and enforce strong passwords.
3. Monitor for Abnormal Activity: Set up continuous monitoring of DNS records and email traffic for signs of exploitation.
4. Educate Users: Raise awareness about phishing attempts and encourage scrutiny of suspicious emails.
5. Conduct Regular Penetration Testing: Evaluate and fortify systems against evolving cyber threats.

This botnet underlines the importance of cybersecurity hygiene in an interconnected world.

The misuse of compromised routers and domains opens the door to widespread damage, from business disruptions to major data breaches.

Organizations must remain vigilant in their security practices, as misconfigurations and outdated software increasingly serve as entry points for sophisticated cyber adversaries.

While Infoblox continues to track this botnet using DNS analysis, this discovery is a wake-up call for businesses and individuals alike.

As threat actors grow more advanced, the responsibility to maintain robust defenses becomes more critical than ever.

For organizations concerned about their domain security, a quick DNS audit can help identify and rectify vulnerabilities.

Proper configuration and regular monitoring of records such as SPF are essential lines of defense in mitigating threats posed by botnets and malspam campaigns.

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