Malicious PDF — malware analysis report

Static analysis result for SHA-256 45334d1bf4a4f35d…

MALICIOUS

PDF

15.7 KB
MD5: fbe7f7e33e17563ec5b87bbc2e51d1af SHA-1: d0f342ec761c715e784ae1ce125f5194c0bd2538 SHA-256: 45334d1bf4a4f35d84c89efaf2c68596a0203b3cda0ff498406e521fe8ba3110
196 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment T1071.001 Web Protocols

This PDF file was flagged by multiple high-severity heuristics, including PDF_EVAL and PDF_JS_LARGE_COMMENT_PADDED_EVAL, indicating the presence of obfuscated JavaScript designed to exploit vulnerabilities. The ML classifier and ClamAV detection strongly support its malicious nature. The embedded JavaScript stream, identified as javascript_obj0006_000.js, likely serves as a stager to download and execute a second-stage payload, as suggested by the 'eval()' call and 'String.fromCharCode' usage within the decoded stream.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
ef7df33fb4b4671537be01bbfcf70352db5b31449da010a999ca6751b4e201c9
pdf-javascript-stream PDF /JS object 6 at offset 0x143 426009 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).