{"id":2610,"date":"2026-04-21T08:04:06","date_gmt":"2026-04-21T08:04:06","guid":{"rendered":"https:\/\/blog.ibvl.in\/index.php\/2026\/04\/21\/a-wav-with-a-payload-tue-apr-21st\/"},"modified":"2026-04-21T08:04:06","modified_gmt":"2026-04-21T08:04:06","slug":"a-wav-with-a-payload-tue-apr-21st","status":"publish","type":"post","link":"https:\/\/blog.ibvl.in\/index.php\/2026\/04\/21\/a-wav-with-a-payload-tue-apr-21st\/","title":{"rendered":"A .WAV With A Payload, (Tue, Apr 21st)"},"content":{"rendered":"
\n

There have been reports of threat actors using a .wav file as a vector for malware<\/a>.<\/p>\n

It’s a proper .wav file, but they didn’t use staganography. The .wav file will play, but you’ll just hear noise:<\/p>\n

\"\"<\/p>\n

That’s because the TAs have just replaced the bytes that encode the sound with the BASE64 representation of their payload:<\/p>\n

\"\"<\/p>\n

Thus I don’t need a .wav parser to extract the encoded payload, I can just use my base64dump.py<\/a> tool:<\/p>\n

\"\"<\/p>\n

The BASE64-decoded payload is an XOR-encoded PE file. So I don’t need to make a custom decoder, I can just perform a known-plaintext attack looking for the DOS header with my xor-kpa.py<\/a> tool:<\/p>\n

\"\"<\/p>\n

The XOR key was found. Thus we can easily dump the decoded PE file and see the MZ header at position 0x08 and a bit further down the DOS header we used in the known-plaintext-attack:<\/p>\n

\"\"<\/p>\n

And my tool pecheck.py<\/a> can extract an analyse the sample<\/a>:<\/p>\n

\"\"<\/p>\n

Didier Stevens
\nSenior handler
\nblog.DidierStevens.com<\/a><\/p>\n

(c) SANS Internet Storm Center. https:\/\/isc.sans.edu Creative Commons Attribution-Noncommercial 3.0 United States License.<\/p><\/div>\n","protected":false},"excerpt":{"rendered":"

There have been reports of threat actors using a .wav file as a vector for malware. It’s a proper .wav file, but they didn’t use staganography. The .wav file will play, but you’ll just hear noise: That’s because the TAs have just replaced the bytes that encode the sound with the BASE64 representation of their […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-container-style":"default","site-container-layout":"default","site-sidebar-layout":"default","disable-article-header":"default","disable-site-header":"default","disable-site-footer":"default","disable-content-area-spacing":"default","footnotes":""},"categories":[90],"tags":[91],"class_list":["post-2610","post","type-post","status-publish","format-standard","hentry","category-cybersecurity","tag-cybersecurity"],"yoast_head":"\nA .WAV With A Payload, (Tue, Apr 21st) - Imperative Business Ventures Limited<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/blog.ibvl.in\/index.php\/2026\/04\/21\/a-wav-with-a-payload-tue-apr-21st\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"A .WAV With A Payload, (Tue, Apr 21st) - Imperative Business Ventures Limited\" \/>\n<meta property=\"og:description\" content=\"There have been reports of threat actors using a .wav file as a vector for malware. 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