Malicious PDF — malware analysis report

Static analysis result for SHA-256 1387fe63944bcdce…

MALICIOUS

PDF

389.1 KB
MD5: c1736de9fe3539493f6b58dc30e177fc SHA-1: 0bf5557de692f5b8b145d683adeb763d062792dc SHA-256: 1387fe63944bcdce870ea8c16fcf73cbd00d801636c5cd2b8384af09cc3369a5
186 Risk Score

Malware Insights

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

The PDF sample contains embedded JavaScript that is obfuscated using string concatenation and a custom Base64 decoding function. The script's primary purpose appears to be downloading and executing a second-stage payload, as indicated by the heuristic firings related to JavaScript execution and exploit indicators. The ClamAV detection of 'Pdf.Exploit.Agent-36175' further confirms its malicious nature.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 5

  • ClamAV: Pdf.Exploit.Agent-36175 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36175
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0008_000.js
7e9643f94972775d08f0beb5daeadf1d5252dc77d8258d69a3f1e3aeb662bfbb
pdf-javascript-stream PDF /JS object 8 at offset 0x1E7 132542 bytes
Detection
ClamAV: Pdf.Exploit.Agent-36175
Obfuscation or payload: unlikely