PDF malware analysis — malicious · b8034ca89128ec1d

MALICIOUS

PDF

4.0 KB

MD5: fb14bc75d545a5178455843ae94373be SHA-1: 9e5f659ae8280482cd9997c4c5d6809628ac9e79 SHA-256: b8034ca89128ec1ded7d87a35ff054683d54181cb09f7c5df6cae43e08a47ce4

96 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains embedded JavaScript, indicated by multiple PDF-specific heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL'. The ML classifier also flagged this PDF as malicious with high confidence. The presence of 'eval()' and 'String.fromCharCode' suggests obfuscated JavaScript code is being executed. Two JavaScript files, 'acroform_b64_00.js' and 'javascript_obj0013_001.js', were extracted, with one being deobfuscated. This JavaScript is likely responsible for downloading and executing a second-stage payload.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 5

eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0013_001.js` `04bbfd764105ece6905c5dda58438dccfaf92483cc109fc7ce973ef23c00901e`	pdf-javascript-stream	PDF /JS object 13 at offset 0x368	6293 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`acroform_b64_00.js` `77a2c5b87961cc397af2120ff8c7bfd4b82cb848ad9f78e18ef2d0b72d068745`	deobfuscated-js	PDF AcroForm base64 (decompressed) at offset 0x99D	3566 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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