PDF malware analysis — malicious · 40c4c8b819b9b083

MALICIOUS

PDF

1.08 MB Created: 2009-03-03 06:02:53 Authoring application: FreePic2Pdf - 1.26

MD5: b9d9dfc99e46e487bf664423723586f6 SHA-1: 0c1b64ee517bdd9cf3b348aac72e85e773e8fa55 SHA-256: 40c4c8b819b9b08322afad158a43d40de67b4f17b92e9093ca7fb0e7cb72d9bc

248 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File T1027 Obfuscated Files or Information T1105 Ingress Tool Transfer

The PDF file contains a critical JBIG2Decode filter exploit (CVE-2009-0658) and a hidden ZIP archive containing executable files. The presence of JavaScript and a hidden ZIP payload strongly suggests the intent is to exploit the PDF reader and execute a secondary payload. The extracted executable names 'VMUnpacker_cn.exe' and 'VMUnpacker_en.exe' indicate a potential unpacking utility, likely used to deobfuscate and run further malicious code.

Heuristics 11

Adobe Reader JBIG2Decode generic heap-spray exploit critical CVE likely CVE_2009_0658_GENERIC_SPRAY

PDF combines JBIG2Decode image streams with JavaScript heap-spray or decoder scaffolding. This is likely CVE-2009-0658-family Adobe Reader JBIG2 exploitation, but it lacks the stricter Reader-9 version gate or decoded page-word shellcode fingerprint required by the exact rule.
JBIG2 + active content high CVE related PDF_JBIG2_ACTIVE_CONTENT

JBIG2Decode appears with JavaScript/XFA/RichMedia — a related indicator for JBIG2 parser-exploit families including CVE-2021-30860 and CVE-2009-0658, but not a unique CVE fingerprint.
Hidden ZIP payload with executable entries inside PDF stream critical PDF_HIDDEN_ZIP_EXECUTABLE_PAYLOAD

PDF stream bytes contain an embedded ZIP archive whose local headers name executable payload files. This is not a normal PDF attachment (/EmbeddedFile); it hides Windows payloads inside an ordinary stream, a strong malware-loader or smuggling pattern.
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
JBIG2Decode filter medium PDF_JBIG2

JBIG2 image decoder present — historically used in zero-click exploits
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.
Embedded file low PDF_EMBEDDED

PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
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.
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
URL http://www.w3.org/1999/02/22-rdf-syntax-ns#
- http://ns.adobe.com/xap/1.0/
- http://ns.adobe.com/pdf/1.3/
- http://purl.org/dc/elements/1.1/
- http://ns.adobe.com/xap/1.0/mm/

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0016_000.js` `430afe865f674b0bf62028757df583ccaa09481c49719805519679d1bd4612ec`	pdf-javascript-stream	PDF /JS object 16 at offset 0x114B40	1006 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`hidden_pdf_zip_off0008aa41.zip` `99d552c032be1885afa18b3016da2384c7265dcdb1cba207da1e86e3334a9347`	pdf-hidden-zip	PDF raw stream ZIP payload at offset 0x8AA41	561405 bytes
`jbig2_00_off000000ad.bin` `2809bfc72508ebc49a3524d03f85cb0dfedf4e3f58284939a5f112b90b10fcc6`	pdf-jbig2-stream	PDF JBIG2 stream at offset 0xAD	3300 bytes

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