Malicious PDF — malware analysis report

Static analysis result for SHA-256 d75f125f366d942f…

MALICIOUS

PDF

15.7 KB
MD5: 51ab8e7631aad5765b92fded52d1531f SHA-1: ee557bb1cab02ac50898feba320afc69e436d310 SHA-256: d75f125f366d942f97187b1b769405ffeba169e3e1c50344a7f005bd3b512e92
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 a large comment-padded eval stager. This JavaScript is designed to execute arbitrary code, as indicated by the 'eval()' and 'String.fromCharCode()' calls. The ClamAV detection 'Pdf.Exploit.Agent-36086' strongly suggests this is a known exploit. The primary function appears to be downloading and executing a second-stage payload, typical of a downloader or initial access exploit.

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
bf1b17b8ae5528298e72f881b8e75021d72cbbd46bb21279a64ed346f0ad590a
pdf-javascript-stream PDF /JS object 6 at offset 0x143 425361 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
50bafa752176938675a141e4af74b18037ee805281e439ba1fa2bdb0973cb38a
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 480 long base64-like blob(s).