Malicious PDF — malware analysis report

Static analysis result for SHA-256 5fb681978de0bab1…

MALICIOUS

PDF

6.4 KB
MD5: e735993f5997bf04dc8061d08395b91d SHA-1: 81c80dd0b73700e30d3057b1a6d32507da08a6eb SHA-256: 5fb681978de0bab1dfe7efcb1b9abf3fd4556f23788f2a62f54d3456b960a860
150 Risk Score

Malware Insights

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

The PDF sample contains JavaScript code that utilizes the `unescape()` function, a common indicator of obfuscation for exploit code. The critical PDF JavaScript exploit cluster heuristic further supports this. The primary purpose appears to be the execution of this script, which likely leads to the download and execution of a second-stage malicious payload. No specific family could be identified.

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_off00000325.bin
24e6f14c9068ce014a054f0a95e4edb4b1631b873643226b242d5eb7f42b89cf		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x325 788 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
42b0a36ec3e61319de8d2b2f0e7e6bdea6bfb732f4843bec2c59dd62c4448e35		 pdf-objstm-decoded PDF /ObjStm 24 0 obj (inflated) 331 bytes

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