PDF malware analysis — malicious · 16cd2744a86d2cf1

MALICIOUS

PDF

20.6 KB

MD5: 85fd162cfa70506bd00d0643409ab259 SHA-1: bc31339fe0c9462e35767a082d1b6d93c2b7646e SHA-256: 16cd2744a86d2cf1f2a1676bcc003651c17472f1497540eb3ae0c49ae83670cc

218 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF file contains obfuscated JavaScript, indicated by the 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL' heuristics, along with a critical 'PDF_JS_EXPLOIT_CLUSTER' finding. The JavaScript code, particularly in 'javascript_obj0005_000.js', uses `String.fromCharCode` and `eval()` to deobfuscate and execute malicious code, likely a second-stage payload. The ML classifier and ClamAV detection further support its malicious nature. The primary attack pattern is likely spearphishing attachment, leading to exploitation for client execution.

Machine Learning

Nyx PDF Classifier malicious score 0.9997

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` `4953f85bdaf3abbd801b577ea80eeb2139c5374fa084c4c3c7ea614ac6bb2c4f`	pdf-javascript-stream	PDF /JS object 5 at offset 0x160	20506 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`javascript_obj0005_001.js` `4f38e7bd5a56004083b9b10e63ce47efdf902d6561afe1c74f5d856492049943`	pdf-javascript-stream	PDF /JS object 5 at offset 0x160	61 bytes

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