Malicious PDF — malware analysis report

Static analysis result for SHA-256 e83f12e9d4904ba3…

MALICIOUS

PDF

15.7 KB
MD5: 1fe5234e948ab79de54728bbb21cfda2 SHA-1: 3d67df260dda9bb8f0ba741515306ad70e4d0c14 SHA-256: e83f12e9d4904ba399bfbd112b4f3a07e7a569961a8e53c384de358575273eff
166 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT, PDF_JS, and PDF_EVAL. The 'Large comment-padded JavaScript eval stager' heuristic suggests a sophisticated obfuscation technique. The presence of two extracted JavaScript files, one deobfuscated, further supports the execution of malicious code. The primary function appears to be the execution of JavaScript, likely to download and execute a secondary payload, as suggested by the ClamAV detection of 'Pdf.Exploit.Agent-36086'.

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
889381310ea23e008f4e0dfe3c3bf950c0a768f60da50a90f3ec105ddb8559d3
pdf-javascript-stream PDF /JS object 6 at offset 0x143 424705 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
35b1ce90587b24895a99d2f1bf2649c31847f101a44cda7a6dde5788f9fabd8f
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262090 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 640 long base64-like blob(s).