PDF malware analysis — malicious · 0ba8ac7bdf3a4e43

MALICIOUS

PDF

6.6 KB

MD5: cb94d005592a138fff6e60946e6d562d SHA-1: c1811ec3c89ae9aa5e258441b7a9c766fe4bf98c SHA-256: 0ba8ac7bdf3a4e437abdcad13192c98bc6652de8f854d3e8c14c7363f88a8e53

86 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF contains embedded JavaScript that is obfuscated using XOR operations and string concatenation. The script reconstructs and calls functions like 'unescape', 'getPageNthWord', 'charCodeAt', 'fromCharCode', and 'substr' to deobfuscate a payload. This payload is then likely executed via 'eval', indicating the document's purpose is to download and run a secondary malicious component. The ML classifier strongly supports the malicious nature of this PDF.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 3

Page-word XOR JavaScript eval stager high PDF_PAGE_WORD_XOR_EVAL_STAGER

PDF JavaScript enumerates rendered page words with getPageNthWord/getPageNumWords, extracts encoded byte fragments, XOR-decodes the stage with char-code helpers, and evals the result. This is an old exploit-kit staging pattern and is not normal document JavaScript.
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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0018_000.js` `64dbb1b26294330f72a9c5b7a7778b4e255c7b7609626eddfee2e06a530f4473`	pdf-javascript-stream	PDF /JS object 18 at offset 0x14F2	1021 bytes

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