Malicious PDF — malware analysis report

Static analysis result for SHA-256 d8c5a5529ab82f26…

MALICIOUS

PDF

337.0 KB Created: 2008-03-03 17:06:20 +08:00 Authoring application: Advanced PDF Repair: http://www.pdf-repair.com
MD5: d80130ed141460bebc9728c687fa6834 SHA-1: 05ab85e833fc13dbe9bb50c64c862461e8145d66 SHA-256: d8c5a5529ab82f26c927377bf616d3afdc2982af9095c115646a8fdb4f306a89
268 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

This PDF file exhibits multiple high and critical heuristic firings related to JavaScript exploits and generic stage recovery, indicating it's designed to execute malicious code. The embedded JavaScript, particularly the deobfuscated stages, strongly suggests the intent to download and execute a second-stage payload. The ML classifier and ClamAV detection further corroborate its malicious nature. While specific IOCs like URLs are not clearly defined due to obfuscation, the presence of multiple JavaScript files points to a multi-stage attack.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9995

Heuristics 11

  • 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: Heuristics.PDF.ObfuscatedNameObject critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Heuristics.PDF.ObfuscatedNameObject
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Generic recovered JavaScript exploit stage high PDF_GENERIC_STAGE_RECOVERY
    Bounded static stage recovery exposed hidden JavaScript through generic transforms such as null-byte collapse, percent decoding, marker replacement, arithmetic character codes, fromCharCode, numeric arrays, numeric-array minus-key decoders, alphabet-index arrays, /Producer half-difference metadata arrays, hex literals, marker-stripped Base64 literals, custom 6-bit XOR table decoders, or repeated-marker hex carriers. This rule is emitted only when the recovered stage contains exploit-like Acrobat JavaScript or shellcode markers.
  • 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.
  • 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
  • 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.pdf-repair.com
    • http://www.pdf-repair.com)/Producer(Advanced
    • http://www.pdf-repair.com)/ModDate(D:20100404092506+08
    • http://www.pdf-repair.com)/ModDate(D:20100404093132+08
    • http://www.pdf-repair.com)/ModDate(D:20100404093243+08
    • http://www.pdf-repair.com)/ModDate(D:20100404093525+08
    • http://www.pdf-repair.com)/ModDate(D:20100404093601+08
    • http://www.pdf-repair.com)/ModDate(D:20100404094947+08
    • http://www.pdf-repair.com)/ModDate(D:20100404095117+08
    • http://www.w3.org/1999/xhtml
    • http://www.xfa.org/schema/xfa-data/1.0/
    • 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://ns.adobe.com/xap/1.0/mm/
    • http://purl.org/dc/elements/1.1/

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0054_000.js
2fe85b93fb9b41eb8a33b9e59056e1b5da436c9a40c19deb91141a24d573bd72		 pdf-javascript-stream PDF /JS object 54 at offset 0x528ED 18211 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
generic_stage_recovery_000.js
b0d81e4d0ecda557b65760b0a3b7fbede8aac2eadd282b730aebdb684e37d3e1		 deobfuscated-js generic stage recovery percent-decode from raw PDF metadata at offset 0x0 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 long base64-like blob(s).
generic_stage_recovery_001.js
9f50ae8b059f3890f4b5cba5d07190203a8e518297219389c8bc5840cbd5a8f0		 deobfuscated-js generic stage recovery percent-decode from decompressed stream at 0x0 at offset 0x0 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 long base64-like blob(s).

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