Malicious PDF — malware analysis report

Static analysis result for SHA-256 737fbb92e8a2b03d…

MALICIOUS

PDF

81.5 KB Created: 2009-05-14 12:40:13 +08:00 Authoring application: PScript5.dll Version 5.2.2 (via Acrobat Distiller 7.0 (Windows))
MD5: 79bc4450f036b23fddc2fc75f2efa6fd SHA-1: da79e6e03e179adcd6f4173c504116029870d833 SHA-256: 737fbb92e8a2b03dc54f8b446db7bc5126cbe38da12c2d910a184afa88396d76
280 Risk Score

Malware Insights

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

This PDF file contains JavaScript that utilizes the unescape() function and performs a heap spray, which is a known technique for exploiting vulnerabilities like CVE-2009-0658 in Adobe Reader. The script's primary function appears to be preparing the environment for the execution of further malicious code, likely a downloaded payload. The ML classifier strongly indicates maliciousness.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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.
  • 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.
  • Optional Content Group with action trigger low PDF_OPTIONAL_CONTENT
    Optional Content Group (layer) co-occurs with an action trigger — content can be selectively hidden from viewers or scanners while the action still fires on open
  • 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/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0011_000.js
60013647f65915440fea2210c9f54b093561f299268f0782c4385d3b3dfe4634		 pdf-javascript-stream PDF /JS object 11 at offset 0x5E3 520 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
javascript_obj0036_001.js
32b1d36f8d1de1a814c809b19720323719b6e3c64e55683553a894782be03aa7		 pdf-javascript-stream PDF /JS object 36 at offset 0x8B27 520 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
jbig2_00_off00001e7d.bin
24d4a1abb0bbed5186bcb0b0bc3ab6478e10fecf75e1fbb01b4d091517ea01ae		 pdf-jbig2-stream PDF JBIG2 stream at offset 0x1E7D 3986 bytes
font_00_sfnt_off000030ec.bin
054efc047363b9aa71725e85e1e2afadc15e8323b274edb5732ed315505f4d74		 pdf-font-stream PDF embedded font (sfnt) at offset 0x30EC 179816 bytes

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