PDF malware analysis — malicious · 5b8379509af26c47

MALICIOUS

PDF

42.7 KB

MD5: 4010d7af7562a49d1f3b4cf6a9109bc3 SHA-1: bf2a870f21207b0c73daea3d9cbbfab6deffb726 SHA-256: 5b8379509af26c476d47cbb450b7b15000f125f6f7edf1f60967f42da8473313

218 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF file contains obfuscated JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL'. The JavaScript attempts to reconstruct strings using 'String.fromCharCode' and 'eval()', a common technique for hiding malicious code. The primary embedded JavaScript stream, 'javascript_obj0005_000.js', is heavily obfuscated but its structure suggests it is designed to download and execute a secondary payload. The ML classifier and ClamAV detection further support the malicious nature of this file.

Machine Learning

Nyx PDF Classifier malicious score 0.9994

Heuristics 8

PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER

PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
ClamAV: Heuristics.PDF.ObfuscatedNameObject critical CLAMAV_DETECTION

ClamAV detected this file as malware: Heuristics.PDF.ObfuscatedNameObject
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution
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.
PDF differential parser failed info PDF_DIFFERENTIAL_PARSE_FAILED

The cross-check parser (pdfminer.six) failed on this file: PDF differential parser failed: PSEOF. Static heuristics still ran and any of their findings above are valid; only the differential cross-check signal is missing.
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_obj0005_000.js` `ba6f658115bacb5fdd4571281908db72c3802a6c20da32e6b75ba6ebb2945de5`	pdf-javascript-stream	PDF /JS object 5 at offset 0x15E	43097 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`javascript_obj0005_001.js` `ab5956e6240b45f2ee1e5dd8976dec7b3be806627a7cb3528ae7c28176751b3c`	pdf-javascript-stream	PDF /JS object 5 at offset 0x15E	61 bytes

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