PDF malware analysis — malicious · 10e98448bc32174b

MALICIOUS

PDF

52.6 KB Created: 2017-11-13 00:19:10 +01:00

MD5: 1c2c95e73c85f00207d0e06d52a934d8 SHA-1: 3afc2e6b0f56e9f1104f26e4f69608c5599c5253 SHA-256: 10e98448bc32174b5074187e1a7273b9f81362bbb93a80648830582147f66625

188 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF sample contains JavaScript that utilizes eval() and String.fromCharCode, indicating an attempt to obfuscate malicious code. This script is likely responsible for downloading and executing a second-stage payload, as suggested by the PDF_JS_EXPLOIT_CLUSTER and PDF_EMBEDDED_SCRIPT_PAYLOAD heuristics. The presence of XFA forms further supports the exploitation vector. Given these indicators, the primary attack pattern is likely spearphishing attachment leading to client-side exploitation.

Machine Learning

Nyx PDF Classifier malicious score 0.9729

Heuristics 10

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.
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
Embedded file low PDF_EMBEDDED

PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
XFA form low PDF_XFA

PDF uses XML Forms Architecture — can contain script logic
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. (matched inside decoded stream)
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. (matched inside decoded stream)
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)
Embedded script payload in PDF stream low PDF_EMBEDDED_SCRIPT_PAYLOAD

PDF stream bytes contain an HTML/XFA <script> tag without accompanying Windows shell-execution primitives — common in accessible XFA forms but worth surfacing for analyst review.
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
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/xap/1.0/mm/
- http://purl.org/dc/elements/1.1/
- http://ns.adobe.com/xdp/
- http://www.xfa.org/schema/xci/3.0/
- http://www.xfa.org/schema/xfa-template/3.0/
- http://www.xfa.org/schema/xfa-data/1.0/
- http://www.xfa.org/schema/xfa-form/2.8/

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`embedded_file_obj0029.bin` `ddb2f0273ff53a78cba698afed0c23add8e219eaa85fecd99611493bebdb4d27`	pdf-embedded-file	PDF EmbeddedFile object 29 at offset 0xC5B3	1237 bytes
`objstm_0035_00.bin` `eeb69e2dadfa00e86ba6af0e6cb511413051e5b08feb63db3edbb93a1dcfb2ad`	pdf-objstm-decoded	PDF /ObjStm 35 0 obj (inflated)	1283 bytes

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