Cybersecurity researchers have identified a wave of attacks targeting outdated versions of the HTTP File Server (HFS) software from Rejetto, aiming to distribute malware and cryptocurrency mining tools. These attacks exploit a critical security flaw known as CVE-2024-23692, which allows hackers to execute arbitrary commands without needing authentication.
CVE-2024-23692 is a high-severity vulnerability discovered by security researcher Arseniy Sharoglazov. It was publicly disclosed in May this year, following a detailed technical report. The flaw is a template injection vulnerability that enables remote attackers to send specially crafted HTTP requests to execute commands on the affected systems. The vulnerability affects HFS versions up to and including 2.3m. In response, Rejetto has issued a warning to users, advising against the use of these versions due to their susceptibility to control by attackers.
Researchers at AhnLab Security Intelligence Center (ASEC) have observed multiple attacks on version 2.3m of HFS. This version remains popular among individuals, small teams, educational institutions, and developers for network file sharing. The attacks likely began after the release of Metasploit modules and proof-of-concept exploits soon after the vulnerability's disclosure.
During these attacks, hackers gather information about the compromised system, install backdoors, and deploy various types of malware. Commands such as "whoami" and "arp" are executed to collect system and user information and identify connected devices. Hackers also add new users to the administrators' group and terminate the HFS process to prevent other threat actors from exploiting the same vulnerability.
In several cases, the XMRig tool, used for mining Monero cryptocurrency, was installed. ASEC researchers attribute one of these attacks to the LemonDuck threat group. Other malware payloads deployed include:
1. XenoRAT: A tool for remote access and control, often used alongside XMRig.
2. Gh0stRAT: Used for remote control and data exfiltration.
3. PlugX: A backdoor associated with Chinese-speaking threat actors, providing persistent access.
4. GoThief: An information stealer that uses Amazon AWS for data exfiltration, capturing screenshots, collecting desktop file information, and sending data to an external command and control server.
AhnLab continues to detect attacks on HFS version 2.3m. Given that the server must be online for file sharing, it remains a lucrative target for hackers. Rejetto recommends users switch to version 0.52.x, which is the latest release despite its lower version number. This version is web-based, requires minimal configuration, and supports HTTPS, dynamic DNS, and administrative panel authentication.
The company has also provided indicators of compromise, including malware hashes, IP addresses of command and control servers, and download URLs for the malware used in these attacks. Users are urged to update their software to the latest version and follow cybersecurity best practices to protect their systems from such vulnerabilities.
By assimilating and addressing these vulnerabilities, users can better secure their systems against these sophisticated attacks.
Among other malware, StripedFly can steal access credentials from targeted systems, and take capture screenshots, obtain databases, private files, movies, or other relevant data, and record audio in real time by breaking into a target's microphone. Interestingly, StripedFly conceals communication and exfiltration between the malware and its command-and-control servers using a novel, proprietary Tor client.
Additionally, there is a ransomware component that has occasionally been used by attackers. Using a modified version of the infamous EternalBlue exploit that was published by the US National Security Agency, it first infects targets.
While StripFly can steal Monera cryptocurrency, that is only a portion of what it is capable of. The researchers found this out last year and thoroughly examined it before making their results public.
Kaspersky researchers Sergey Belov, Vilen Kamalov, and Sergey Lozhkin wrote in the post, "What we discovered was completely unexpected; the cryptocurrency miner was just one component of a much larger entity."
According to the researchers, the platform is essentially "a hallmark of APT malware" since it has update and delivery capabilities via reliable services like Bitbucket, GitHub, and GitLab—all of which use specially encrypted archives—as well as an integrated Tor network tunnel for communication with command-and-control (C2) servers./ The researchers further notes that discovering the breadth of StripedFly is ‘astonishing,’ taking into account its successful evasion from getting detected in six years.
The main structural component of the malware is a monolithic binary code that could be expanded by the attackers through different pluggable modules. Every module, whether for added functionality or to offer a service, is in charge of setting up and maintaining its own callback function in order to communicate with a C2 server.
The platform initially emerges on a network as a PowerShell that seems to leverage a server message block (SMB) attack, which looks to be a modified variant of EternalBlue. EternalBlue was first discovered in April 2017 and is still a danger to unpatched Windows systems.
Depending on the availability of its PowerShell interpreter and certain privileges made available in the process, the malware uses a variety of methods for persistence. The researchers notes that, "typically, the malware would be running with administrative privileges when installed via the exploit, and with user-level privileges when delivered via the Cygwin SSH server," the researchers wrote.
The functionality modules are wide and varied, giving attackers a range of options that enable them to continuously monitor a victim's network activity. The modules include the Monero cryptominer mentioned earlier, as well as a variety of command handlers, a credential harvester, repeatable tasks that can record microphone input, take screenshots, and carry out other tasks on a scheduled basis, a reconnaissance module that gathers a lot of system data, and SMBv1 and SSH infectors for worming and penetration capabilities.