Malicious PDF — malware analysis report

Static analysis result for SHA-256 04782dd32f7a9cb9…

MALICIOUS

PDF

5.3 KB
MD5: 9121096f174fbbb714e1c721484d63a4 SHA-1: e9b9cb204916f032be09aa5d07b748bf7258337e SHA-256: 04782dd32f7a9cb95912f1547eb76e8b757218fbdda4b8a4bc89e3c7dc3f9d07
204 Risk Score

Malware Insights

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

The sample is a PDF file that contains embedded JavaScript, indicated by multiple PDF_JAVASCRIPT and PDF_JS heuristics. The PDF_JS_EXPLOIT_CLUSTER and ML_NYX_PDF_MALICIOUS heuristics, along with ClamAV detection as Pdf.Exploit.Agent-36178, confirm its malicious nature. The JavaScript is likely used to exploit a vulnerability within the PDF reader to execute arbitrary code, potentially downloading and running a second-stage payload.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 8

  • 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.
  • ClamAV: Pdf.Exploit.Agent-36178 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36178
  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
  • 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.
  • 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.
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
  • ASCII85Decode filter (with exploit indicators) low PDF_FILTER_85
    ASCII85 encoding filter present alongside exploit delivery indicators — uncommon outside of obfuscation
  • PDF differential parser failed info PDF_DIFFERENTIAL_PARSE_FAILED
    The cross-check parser (pdfminer.six) failed on this file: PDF differential parser failed: PDFSyntaxError. Static heuristics still ran and any of their findings above are valid; only the differential cross-check signal is missing.