Malicious PDF — malware analysis report

Static analysis result for SHA-256 759992c22f9f2b43…

MALICIOUS

PDF

7.0 KB
MD5: f156deedc650c2d878fb3e4cc50ce1be SHA-1: eec013eeaed8bc47c8779c7ac70f9f73d49a41b4 SHA-256: 759992c22f9f2b43679313523cf8f2fd372f242ade48b4f991590deb4aabcee6
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, found at offset 0x850 and decompressed as 'stream_002_off00000327.bin', utilizes an 'unescape()' call, a common technique in PDF exploits. This suggests the script is designed to download and execute a secondary payload, aligning with the 'Exploitation for Client Execution' technique. Given the nature of PDF exploits, 'Spearphishing Attachment' is a likely initial access vector.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9825

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
8d8556634066588414fd8b15e36ac3534e585aa573c1600cdcede6e7377003de		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x327 3109 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).
objstm_0024_00.bin
7117453d8c7fedbf86f03d2e5fe19c26f49ff73e9a657dd01473aeeda81d9dcf		 pdf-objstm-decoded PDF /ObjStm 24 0 obj (inflated) 331 bytes

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