Malicious PDF — malware analysis report

Static analysis result for SHA-256 7924875f263ee0fc…

MALICIOUS

PDF

22.3 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode
MD5: a06bec31013831240363d07df1292cd2 SHA-1: fae39f480d1e57470c2c09c3e892185bfbd5bf80 SHA-256: 7924875f263ee0fc47da74ebbb9e33e6a8d7a37188d1e2aac77cd8ee84089da3
96 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious File: Malicious File

The PDF file contains embedded JavaScript, identified by the PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream utilizes `eval()` and `String.fromCharCode`, indicating obfuscation and dynamic code execution. The ML classifier strongly flags this PDF as malicious. The primary function of the embedded script appears to be downloading and executing a second-stage payload, as suggested by the obfuscated nature and the use of `eval()`.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 5

  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • 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.
  • 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_obj0001_000.js
fdf43f8639c03e6e81cc52dfcd38f23286cdee815095ed0247f432d5cf7dc3c3
pdf-javascript-stream PDF /JS object 1 at offset 0xA 537 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s).