Malicious PDF — malware analysis report

Static analysis result for SHA-256 041056c758e3cc80…

MALICIOUS

PDF

19.3 KB Created: 2012-09-17 23:33:20 +04:00 Authoring application: Adobe Acrobat 10.0 (via Acrobat Web Capture 10.0)
MD5: 85e07be0bf47037d57f0dc759341a4c8 SHA-1: 0810c735c11850851ad426853dc36618e211df6b SHA-256: 041056c758e3cc8092673f006685426669a0b41b06ac77fb0260613549b4808d
118 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript that is heavily obfuscated using String.fromCharCode. This script is designed to execute an exploit, likely leading to the download and execution of a secondary payload. The ML classifier and heuristic firings strongly indicate malicious intent, but the exact nature of the payload and its ultimate destination could not be determined due to obfuscation.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 6

  • 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.
  • 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.
  • 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/
    • http://www.iec.ch

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0019_000.js
717d15ce7ab9847cda591f19858998204176ba3408965f21718c217582aba09b		 pdf-javascript-stream PDF /JS object 19 at offset 0x2DE 8220 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 10 long base64-like blob(s).
icc_00_off000029b5.icc
653b586c4707574ffcd648ba35494daed2c76ceafcf4c07d315ed961b1dc347f		 pdf-icc-profile PDF ICC profile at offset 0x29B5 408 bytes
icc_01_off00002c50.icc
2b3aa1645779a9e634744faf9b01e9102b0c9b88fd6deced7934df86b949af7e		 pdf-icc-profile PDF ICC profile at offset 0x2C50 3144 bytes

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