Malicious PDF — malware analysis report

Static analysis result for SHA-256 5a5cc85dac0f8f07…

MALICIOUS

PDF

14.5 KB
MD5: 87c55a407efb458b325a28c5bb79bbad SHA-1: e53e9f786ac95d1bb55003e35875d1c550a17bfa SHA-256: 5a5cc85dac0f8f0749451069c450056ac08c6da2b6b1f8e845f8d4540985bc5f
216 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 that utilizes String.fromCharCode and eval() to execute obfuscated code. This JavaScript is designed to exploit a known PDF vulnerability, leading to the execution of a second-stage payload. The ClamAV detection and ML classifier strongly indicate malicious intent, likely delivered via spearphishing.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 7

  • 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.
  • ClamAV: Pdf.Exploit.Dropped-94 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Dropped-94
  • 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_obj0076_000.js
c28effae366bd4b2a63fe29aea090a07947ae4e73aa9efc1cf87e16e006e7288
pdf-javascript-stream PDF /JS object 76 at offset 0x38AB 144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).