Malicious PDF — malware analysis report

Static analysis result for SHA-256 3c8a4b5651557f1d…

MALICIOUS

PDF

3.4 KB First seen: 2026-05-11
MD5: f836337404885c0c18600ad0ee173c7e SHA-1: 538e3118eac2211631d1aa71a2c8ac9c82214b41 SHA-256: 3c8a4b5651557f1d9799ad493843ffa49785a42219cab8299926c342a24bd15d
118 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

The ML classifier strongly indicates maliciousness, supported by heuristic firings for JavaScript actions and the use of ASCIIHexDecode filters, which are common in PDF exploits. The presence of JavaScript suggests an attempt to execute malicious code, likely to download a second-stage payload or exploit a vulnerability within the PDF reader.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 3

  • JavaScript action low 1 related finding PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • PDF JavaScript rebuilds a builtin via replace() to run a char-code array critical PDF_JS_REPLACE_OBFUSCATED_CHARCODE_BUILDER
    Decoded PDF JavaScript resolves a String builtin from a junked literal — e.g. String['eQvoaol3'.replace(/[3oQS5]/g,'')] yielding fromCharCode/eval — and feeds a large numeric char-code array through it to rebuild and execute the next stage. Dynamically reconstructing a builtin name by stripping junk characters has no benign purpose; paired with the char-code payload array it is an unambiguous obfuscated-JavaScript exploit dropper.
  • 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