PDF malware analysis — malicious · e40585444e67dfb9

MALICIOUS

PDF

56.2 KB

MD5: 9a39419cb7fa592207890ccc275a501a SHA-1: ad011180065e55bf19383a1242c5a2f24ffd2ea4 SHA-256: e40585444e67dfb93445d57839a2338d10c4d0b706dd7c75cd1905574d1c78e9

166 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File Execution: Malicious File T1566.002 Phishing: Spearphishing Attachment

This PDF file is flagged as malicious by ClamAV, specifically detecting Win.Exploit.CVE_2018_4990-6599478-0. The presence of embedded JavaScript, particularly using String.fromCharCode and an AcroForm button with an action trigger, indicates an attempt to execute code. The ML classifier also strongly suggests maliciousness. The primary attack vector appears to be exploiting CVE-2018-4990 via the JPXDecode filter, which is a known vulnerability in Adobe products.

Machine Learning

Nyx PDF Classifier malicious score 0.9198

Heuristics 8

JPXDecode + active content — JPEG2000 CVE-family indicator high CVE related PDF_JPX_CVE_2018_4990_RELATED

PDF uses /JPXDecode (JPEG2000) alongside JavaScript, XFA, or RichMedia indicators. This matches the delivery pattern for Adobe Reader JPEG2000 parser exploit families, including CVE-2018-4990, but does not prove the exact malformed JP2/JPX primitive.
ClamAV: Win.Exploit.CVE_2018_4990-6599478-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Exploit.CVE_2018_4990-6599478-0
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)
AcroForm button with action trigger low PDF_ACROFORM_BUTTON

PDF contains a /Btn form field together with a SubmitForm/URI/Launch/JS trigger — this is the building block of fake 'Download' or 'Open' button overlays used in PDF phishing lures
PDF paints image(s) but contains no text operators info PDF_IMAGE_ONLY_LURE

PDF has 1 image XObject(s) and the content stream contains no text-emitting operators (BT/ET, Tj, TJ, ', ") in either raw bytes or decompressed streams — this is the screenshot-as-PDF pattern used to bypass text-based scanners and to deliver instructions purely through rendered pixels. It is informational unless paired with invisible links or risky URI context.
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_obj0014_000.js` `1cff7b0fe2a04d356c7100013d88035064145a1de4d5f8f9f8e8b21d6a394a7e`	pdf-javascript-stream	PDF /JS object 14 at offset 0x1364	397874 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`font_00_cff_off0000d761.bin` `3ad89875e6fb7800b92b2a7d51b20b4698616ec3f17bd584488b4745cd64e011`	pdf-font-stream	PDF embedded font (cff) at offset 0xD761	1578 bytes

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