A recently discovered zero-day vulnerability in Cleo’s file transfer software has placed numerous businesses at considerable risk for data theft, highlighting the severity of cybersecurity flaws in widely-used enterprise solutions. The zero-day bug, identified as CVE-2024-50623, has been actively exploited by threat actors to execute remote code and infiltrate corporate networks. Initially reported by the security vendor Huntress, the flaw predominantly affects the Cleo Harmony, VLTrader, and LexiCom products following an incomplete patch rolled out in October. Investigations revealed that attackers began exploiting this vulnerability as early as December 3, 2024, with activity reaching its peak by December 8. Industries such as consumer products, food and beverage, trucking, and shipping have reported compromises of their systems.
In light of this significant breach, Cleo urgently instructed customers to update to version 5.8.0.21, which was believed to address additional security gaps. However, Huntress deemed this patch insufficient in mitigating the threat. Cleo subsequently confirmed that versions up to 5.8.0.23 were vulnerable to a new form of exploit, characterized by an unauthenticated malicious host vulnerability with a new CVE pending. This ongoing vulnerability continued to pose a remote code execution (RCE) risk, and as of now, Cleo has yet to release a definitive patch. Businesses using these affected versions need to remain vigilant and adopt immediate security measures to prevent further breaches.
Immediate Mitigation Strategies
In response to this critical security issue, Rapid7 issued recommendations to help organizations protect themselves from the exploit. They advised the immediate removal of affected Cleo products from public internet access, urging businesses to position these products behind a robust firewall. Additionally, Huntress recommended disabling Cleo’s Autorun Directory, as this action could prevent the attack chain’s execution, further hindering the threat actors’ ability to exploit the flaw. By following Huntress’s advice, businesses could effectively curb unauthorized actions performed by the attackers.
Beyond these immediate actions, Rapid7 emphasized reviewing Huntress’s findings for any signs of post-exploitation activity within affected environments. They urged organizations to scrutinize their systems for suspicious actions since December 3, with a particular focus on any anomalies or indications of compromised data. By conducting these investigations, companies could better understand the extent of the breach and implement additional security measures to safeguard their information. The urgency of these recommendations underscores the severity of the discovered exploit and the critical need for proactive cybersecurity practices.
Patterns of Cyber Exploitation
The current campaign shares similarities with past zero-day exploits orchestrated by the notorious Clop cybercrime group, known for their attacks on file transfer software such as MOVEit, GoAnywhere, and Accellion FTA. These previous attacks highlighted the vulnerabilities in file transfer systems and the potential for significant data breaches and theft. The similarities in the modus operandi suggest that the same threat actors may be responsible for this latest string of breaches.
Further complicating the situation are unconfirmed reports suggesting that the Termite group, previously linked to attacks on Blue Yonder, might be behind the zero-day exploit targeting Cleo software. This speculation raises concerns about the growing sophistication and capabilities of cybercriminals. The persistence and adaptability of these groups demonstrate the evolving nature of cyber threats and the continuous need for vigilance and advanced cybersecurity strategies.
The Path Forward
A newly found zero-day vulnerability in Cleo’s file transfer software has left many businesses vulnerable to data theft, highlighting critical cybersecurity flaws in popular enterprise tools. The zero-day bug, known as CVE-2024-50623, has been actively exploited by cybercriminals to run remote code and break into corporate networks. Security firm Huntress first reported the flaw, which mainly impacts Cleo Harmony, VLTrader, and LexiCom products due to an incomplete patch issued in October. Investigations revealed that the exploit began on December 3, 2024, peaking by December 8. Sectors like consumer products, food and beverage, and shipping have reported system breaches.
Following this major breach, Cleo urged customers to update to version 5.8.0.21, aimed at closing security gaps. However, Huntress found this patch lacking in threat mitigation. Cleo later confirmed that versions up to 5.8.0.23 were susceptible to a new exploit, marked by an unauthenticated malicious host vulnerability with a CVE pending. This ongoing issue continues to pose a remote code execution (RCE) risk. As of now, Cleo hasn’t released a definitive fix, so businesses using these versions must stay vigilant and implement immediate security measures.