A researcher has discovered a pair of new Magecart-style web skimmers, each one featuring an evasion technique that's not typically employed by this breed of malware: steganography and the transfer a data via the WebSocket protocol.
The researcher, who uses the handle @AffableKraut, posted his two findings on Twitter last month, prompting the team from Malwarebytes to further analyze the threats and report the findings.
According to Malwarebytes, the steganography-based skimmer is the first documented skimmer to use this technique, which commonly involves hiding code within harmless-looking imagery.
In a Dec. 26 tweet, @AffableKraut said a colleague of his found the skimmer while searching through SIEM data. "The skimmer group uploads or modifies an existing image and appends the JS code," the researcher says. In this case, the image appears to be an innocuous "free shipping" ribbon, which was observed on a shopping site.
On Dec. 16, @AffableKraut posted his findings on the other web skimmer, which at the time appeared to still be in development and didn't always work as intended. The skimmer is 840 lines long "and there's a fair amount of minified and somewhat obfuscated code," the researcher noted in a series of tweets describing the threat.
But unique to this malicious tool is its ability to use the WebSocket communication protocol to both load payloads and exfiltrate checkout data over a TCP connection.
"The goal is to conceal a connection to a server controlled by the criminals over a WebSocket," explains Segura's Malwarebytes post.
@AffableKrau was able to link a single domain, bulksuppchat[.]com, to the threat, but could not tie this particular domain to any known Magecart group.