PDF malware analysis — malicious · cb0b68e8fd354783

MALICIOUS

PDF

2.1 KB

MD5: e37c4e9c4b83d2f63da41f8c6dd6eef6 SHA-1: 5cdb8c1dfbcbdbe15205ab4bc11d5fb299374c6b SHA-256: cb0b68e8fd3547832ca4b2aefe66ae52a3b2f3081e30315378f850d9fb4fd864

136 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1027 Obfuscated Files or Information

The PDF contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream utilizes `eval()` and `unescape()` functions, along with `String.fromCharCode`, suggesting obfuscation to hide malicious activity. The ML classifier strongly flags this PDF as malicious. The primary function of the embedded script appears to be downloading and executing a second-stage payload, as evidenced by the obfuscated nature and the presence of an extracted JavaScript file. The specific URL or execution details are not directly discernible due to heavy obfuscation.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 6

eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits (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. (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.

Filename	Kind	Source	Size
`javascript_obj111611_000.js` `9864171cc4152f5d3e5671809dd40cebe1cf9319d0b8bfb0abd003cff50482db`	pdf-javascript-stream	PDF /JS object 111611 at offset 0x759	332 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).

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