Malicious PDF — malware analysis report

Static analysis result for SHA-256 726bdc5c8ba8d98b…

MALICIOUS

PDF

297.2 KB Created: 2009-03-13 16:50:38 +08:00 Authoring application: Acrobat Web Capture 8.0
MD5: 6ade3ccf2a871c4f3b305c6322fd165e SHA-1: 9daa3159363dedd91d56484fd254f2d9054ae2d0 SHA-256: 726bdc5c8ba8d98b685bd282801fcc608646363d2c9e2c6a5180922945c0b796
332 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.007 JavaScript

This PDF file contains embedded JavaScript that leverages the unescape function, a known indicator of exploit activity. The heuristics indicate a critical vulnerability, CVE-2009-0658, related to Adobe Reader's JBIG2Decode filter and JavaScript heap spraying. The script's primary function appears to be preparing for and executing a heap spray, a common technique used to facilitate the exploitation of memory corruption vulnerabilities for client execution.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 11

  • Adobe Reader JBIG2Decode heap-spray exploit critical CVE likely CVE_2009_0658
    PDF combines JBIG2Decode image streams with a Reader 9 JavaScript heap-spray stage. This is the in-the-wild Adobe Reader/Acrobat JBIG2Decode exploit shape associated with CVE-2009-0658.
  • 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.
  • 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: Pdf.Dropper.Agent-5303070-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Dropper.Agent-5303070-0
  • 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.
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • 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://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/pdf/1.3/

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0027_000.js
266e00ca3d7ec0109b0318dd8d869c90daf6a2ec1208ffd2c74bb2ce91900b1d		 pdf-javascript-stream PDF /JS object 27 at offset 0x6BCC 1808 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s).
stream_001_off00002374.bin
6a71966cad617bfb05c2fc57e09517130f7abf80fb7d2cd8d6f9a72dd0ff8cc6		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x2374 8958 bytes
jbig2_00_off000055da.bin
44d3b1bc815caafdba2bfeefb53935563d8867778ab3809a6d2aa0f2943e5336		 pdf-jbig2-stream PDF JBIG2 stream at offset 0x55DA 4945 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.73, consistent with packed or encrypted content.

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