Malicious PDF — malware analysis report

Static analysis result for SHA-256 737cb438fa890c68…

MALICIOUS

PDF

6.4 KB
MD5: 538dd6dbe3f86c2bb8f5716133677c8e SHA-1: 81b3e24df83fa450031d28b775529041bb4a0506 SHA-256: 737cb438fa890c681810ff7a4f6a63bf870710bb4a7e74fc5b9c369635fe22db
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 'PDF_UNESCAPE' firing suggests obfuscated JavaScript is present, likely intended to exploit a vulnerability for client execution. While no specific URLs were found to be malicious, the presence of JavaScript and exploit indicators points to a downloader or dropper functionality, hence the classification as an unknown family.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9833

Heuristics 5

  • JavaScript action low 2 related findings 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)
  • 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.
  • 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# In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_002_off00000325.bin
5fb65bbfb94d0626eb26ea3602b89cddd20f2168a14386761d833205244e4e4a		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x325 963 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
1d5e2f44365bd95c531c7a071c53851aa50b501a0a84a2890dc13b13af03fbaa		 pdf-objstm-decoded PDF /ObjStm 24 0 obj (inflated) 331 bytes

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