Rewterz Threat Alert – Malicious Payloads – Hiding Beneath the WAV

Severity

Medium

Analysis Summary

BlackBerry Cylance Threat Researchers recently discovered obfuscated malicious code embedded within WAV audio files. Each WAV file was coupled with a loader component for decoding and executing malicious content secretly woven throughout the file’s audio data. When played, some of the WAV files produced music that had no discernible quality issues or glitches. Others simply generated static (white noise).

The WAV file loaders can be grouped into the following three categories.

Loaders that employ Least Significant Bit (LSB) steganography to decode and execute a PE file.
Loaders that employ a rand()-based decoding algorithm to decode and execute a PE file.
Loaders that employ rand()-based decoding algorithm to decode and execute shellcode.
Each approach allows the attacker to execute code from an otherwise benign file format. These techniques demonstrate that executable content could theoretically be hidden within any file type, provided the attacker does not corrupt the structure and processing of the container format. Adopting this strategy introduces an additional layer of obfuscation because the underlying code is only revealed in memory, making detection more challenging.

Impact

Exposure of sensitive information

Indicators of Compromise

SHA256

• 595A54F0BBF297041CE259461AE8A12F37FB29E5180705EAFB3668B4A491CECC
• 843CD23B0D32CB3A36B545B07787AC9DA516D20DB6504F9CDFFA806D725D57F0
• DA581A5507923F5B990FE5935A00931D8CD80215BF588ABEC425114025377BB1
• DB043392816146BBE6E9F3FE669459FEA52A82A77A033C86FD5BC2F4569839C9
• 7DC620E734465E2F5AAF49B5760DF634F8EC8EEAB29B5154CC6AF2FC2C4E1F7C

Remediation

• Block all threat indicators at your respective controls.
• Always be suspicious about emails sent by unknown senders.
• Never click on the links/attachments sent by unknown senders.