BlueAlpha, a Russian state-sponsored advanced persistent threat (APT) group, has recently been identified as evolving its malware delivery chain to exploit Cloudflare Tunnels. The primary aim of this transition is to infect victims with its proprietary GammaDrop malware.
Cloudflare Tunnels, a secure tunneling software, enables the connection of resources to Cloudflare’s network without the need for a publicly routable IP address. This functionality is designed to safeguard web servers and applications from distributed denial-of-service (DDoS) attacks and other direct cyber threats by protecting their origins.
However, the downside to this protective mechanism is that, like other legitimate cloud tools, it can be manipulated by malicious actors such as BlueAlpha. The group utilizes Cloudflare Tunnels to conceal its GammaDrop staging infrastructure from conventional network detection methods, as highlighted by the Insikt Group at Recorded Future.
According to an analysis by the Insikt Group, Cloudflare provides the tunneling service for free through the TryCloudflare tool. This tool allows users to create a tunnel using a randomly generated subdomain of trycloudflare.com and route all requests through the Cloudflare network to the corresponding web server.
BlueAlpha leverages the cloaked infrastructure to execute HTML smuggling attacks that evade email security systems and implements DNS fast-fluxing to complicate disruptions to its command-and-control (C2) communications. Ultimately, this elaborate scheme facilitates the deployment of the GammaDrop malware, which facilitates data exfiltration, credential theft, and unauthorized network access.
The group, which has connections to other Russian threat groups like Trident Ursa, Gamaredon, Shuckworm, and Hive0051, made its debut in 2014 and has recently been targeting Ukrainian organizations through spearphishing campaigns. BlueAlpha has been utilizing the custom VBScript malware GammaLoad since at least October 2023.
To counter such threats, the Insikt Group has proposed several mitigation strategies, including enhancing email security to block HTML smuggling techniques, flagging suspicious HTML event attachments, applying application control policies to prevent malicious use of mshta.exe and untrusted .lnk files, and implementing network rules to identify requests to trycloudflare.com subdomains.
In conclusion, the evolving tactics of BlueAlpha underscore the persistent and sophisticated nature of cyber threats posed by state-sponsored APT groups. As organizations strive to fortify their cybersecurity defenses, vigilance, preparedness, and proactive measures are essential to thwarting such malicious activities.