Malicious PDF — malware analysis report

Static analysis result for SHA-256 18fcb166bfb4fa92…

MALICIOUS

PDF

6.8 KB
MD5: 33313570e47744aa0d8691e828c24abe SHA-1: bf7e60cbbdb337f94876327da012c14e594f335f SHA-256: 18fcb166bfb4fa9249393d0f08b072627f6a1bcbd0b7ef608aeecf97c3b85c63
150 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT' and 'PDF_JS_EXPLOIT_CLUSTER'. The JavaScript stream, identified as 'stream_003_off00000717.js', is likely responsible for exploiting a vulnerability within the PDF reader to achieve code execution. The ML classifier also strongly suggests maliciousness. While no specific URLs were extracted for payload delivery, the presence of obfuscated JavaScript points towards a downloader or exploit execution pattern.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9833

Heuristics 6

  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules. (matched inside decoded stream)
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules. (matched inside decoded stream)
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/pdf/1.3/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_002_off00000327.bin
8297a16d93dcfc672beb9232d545cf625ed91a1c4aabc9a705750e498af91796		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x327 1487 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
stream_003_off00000717.js
8c3df86777de0e9c6e976a1f37fe38a01dc10146de13edacca40048ed3db986b		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x717 407 bytes

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