PDF malware analysis — malicious · 51e30eaf10f64c66

MALICIOUS

PDF

4.0 KB

MD5: f3c67357b59d47f09ce747e4bcf22055 SHA-1: 7392b2659ab8f44d26763659ddb067b12511a63d SHA-256: 51e30eaf10f64c6629c1ebdeaa09694f637952bf67c6e39455e169c6bd8dc72d

96 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious File: User Execution: Malicious File

The PDF document contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The ML classifier strongly flagged this PDF as malicious. The JavaScript stream, specifically 'acroform_b64_00.js', utilizes eval() and String.fromCharCode, suggesting obfuscation to hide its true functionality. The primary intent appears to be downloading and executing a second-stage payload from a remote source, as evidenced by the obfuscated script and the ML classifier's output. No specific family could be identified.

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` `7395d06225365dd1f1d1d2f7f44abfca03f7baeaf425eb166fa4e5710d380f2b`	pdf-javascript-stream	PDF /JS object 13 at offset 0x368	6333 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` `933b06ef38d46443164febdfb00cfc509505b0e8aa1d6fb105dd10737f78e4ec`	deobfuscated-js	PDF AcroForm base64 (decompressed) at offset 0x99D	3597 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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