Malicious PDF — malware analysis report

Static analysis result for SHA-256 8f46f8b6d8587b91…

MALICIOUS

PDF

118.6 KB
MD5: ac06e6cb03dbfd0bcd4330d73dde2c81 SHA-1: 2b3073c498504fbb957e1265648b7fc9bc5f09ed SHA-256: 8f46f8b6d8587b917b85b547022c964285263c23810e36efcced3e75008fc0a8
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript, including calls to eval() and String.fromCharCode, which are indicative of obfuscation and execution of malicious code. The heuristic 'PDF_JS_LARGE_COMMENT_PADDED_EVAL' specifically points to a JavaScript eval stager. This suggests the primary function of the PDF is to exploit a vulnerability and execute this JavaScript, likely to download and run a second-stage payload. The ClamAV detection further confirms its malicious nature.

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Large comment-padded JavaScript eval stager high PDF_JS_LARGE_COMMENT_PADDED_EVAL
    PDF JavaScript contains a very large stream padded with long random-looking block comments around String.fromCharCode and eval. This is an exploit-kit obfuscation shape used to bury a decoder and recovered stage inside noise, not normal PDF form automation.
  • 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)
  • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
e2352087e78bf71cda619a4892ddda2fbba00e88434134cfde9733efe525b706
pdf-javascript-stream PDF /JS object 6 at offset 0x143 626322 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 42 long base64-like blob(s).
legacy_pdfkit_stage_000.js
8e6142cf091d03bc8580f0c5f4dcea499069cd9414a909b2e413bf7f252cd64d
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 580 long base64-like blob(s).