Malicious PDF — malware analysis report

Static analysis result for SHA-256 0312e8afb31a6522…

MALICIOUS

PDF

23.3 KB
MD5: 648fced2ee7252d4d96356efe639734b SHA-1: 6a45ca0bf03b50cb304fa4d59e9ecb85681d1e08 SHA-256: 0312e8afb31a6522ec5c7ed38c09795f1a420d030bc59f23a358c1248fe4cbf1
224 Risk Score

Malware Insights

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

The PDF sample contains obfuscated JavaScript that utilizes `unescape()` and `eval()` to execute arbitrary code. The script attempts to deobfuscate and then execute a payload, likely a second-stage downloader. The ML classifier strongly indicates maliciousness, and the combination of JavaScript execution and exploit cluster heuristics points to a common PDF exploitation technique.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 9

  • 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.
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • 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
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj3332_000.js
a105524e6b35a3c7073fa1b7ddac1213d09b678be79c3d2a6932bf8e2a597a30
pdf-javascript-stream PDF /JS object 3332 at offset 0x5AB5 312 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s).