PDF malware analysis — malicious · 38c23bbcccba376c

MALICIOUS

PDF

80.9 KB

MD5: dc83660c21a57eb4b43e72f964598ec6 SHA-1: 7e790584b2488f10d844abe7055ea5d82273f4dc SHA-256: 38c23bbcccba376cf4d2d14d72e9dc52b8728b9ea62db9497ac377f944f56a8b

84 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment

This PDF file was flagged as malicious by an ML classifier and exhibits multiple indicators of malicious JavaScript. The embedded JavaScript, particularly within the 'deobfuscated.js' artifact, likely contains code designed to download and execute a second-stage payload. The presence of PDF-specific heuristics like ASCIIHexDecode filters further supports the exploitation attempt. The exact nature of the payload or its delivery URL could not be definitively determined due to obfuscation, but the overall pattern suggests a drive-by download or spearphishing attack.

Machine Learning

Nyx PDF Classifier malicious score 0.9998

Heuristics 6

ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX

Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
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.
XFA form low PDF_XFA

PDF uses XML Forms Architecture — can contain script logic
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.
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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0002_000.js` `00d83f0df12dd0145d49c2412a9ed675e811ac74df112e5d8f8ec75f6ce39fa6`	pdf-javascript-stream	PDF /JS object 2 at offset 0x12F63	4690 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).
`acroform_b64_00.js` `2dcc302789541914f37753c067c2c4ea2237a5b048127e1f3f24d5698bb1be31`	deobfuscated-js	PDF AcroForm base64 (raw) at offset 0x13367	2803 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `1e75e998f745c6cebbf4af505d5536ed100658c300c2c72f8fd9999c870e6ab8`	deobfuscated-js	PDF JavaScript deobfuscation pass	399351 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 6 long base64-like blob(s).

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