A financially motivated campaign is actively targeting vulnerable SSH servers with the aim of covertly ensnaring them into a proxy network. The attackers leverage SSH for remote access and employ malicious scripts to silently enlist victim servers into a peer-to-peer proxy network.
Unlike cryptojacking, this technique known as proxyjacking enables threat actors to utilize the victim’s unused bandwidth for running various services as a peer-to-peer node, offering reduced resource load and minimizing the risk of detection.
Akamai researcher Allen West highlights the serious implications of proxyjacking, describing it as a stealthier alternative to cryptojacking.
The anonymity provided by proxyware services, which can route traffic through intermediary nodes, poses a double-edged sword as it can be exploited by malicious actors to obfuscate the source of their attacks. Akamai discovered the proxyjacking campaign on June 8, 2023, and found that the attackers breach susceptible SSH servers and deploy an obfuscated Bash script.
This script fetches necessary dependencies from a compromised web server, disguising the curl command-line tool as a CSS file (“csdark.css”). The script actively terminates competing instances of bandwidth-sharing services and launches Docker services that utilize the victim’s bandwidth for profits.
Additionally, the examination of the web server reveals its use for hosting a cryptocurrency miner, indicating the involvement of threat actors in both cryptojacking and proxyjacking attacks.
While proxyware itself is not inherently malicious, Akamai emphasizes that some companies fail to properly verify the sourcing of IP addresses in their networks and even occasionally suggest installing the software on work computers.
When applications are installed without user knowledge or consent, cybercriminals gain control over multiple systems, generating illegitimate revenue.
Allen West emphasizes the continued effectiveness of old techniques when combined with new outcomes and underscores the importance of standard security practices such as strong passwords, patch management, and meticulous logging as effective prevention mechanisms.
