Malicious PDF — malware analysis report

Static analysis result for SHA-256 5b4decd596227831…

MALICIOUS

PDF

11.5 KB First seen: 2026-05-07
MD5: 0b727dcdb59fe469e49fafce64f7a562 SHA-1: f6457ff829b060e3cddcf05aae19e6a2edeb0f8f SHA-256: 5b4decd596227831b7c667661238fe558467f7e0aea359bb4c9076db989579d0
76 Risk Score

Malware Insights

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

The PDF contains a malformed active-content stream, indicated by the 'PDF_MALFORMED_EXPLOIT_STREAM_LENGTH' heuristic, and is flagged as malicious by an ML classifier. This suggests the document is designed to exploit vulnerabilities to execute code. While no specific script was extracted, the presence of embedded files and a suspicious URL points towards a downloader or exploit delivery mechanism.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 5

  • Malformed active-content stream length medium PDF_MALFORMED_EXPLOIT_STREAM_LENGTH
    A PDF stream that carries active/exploit-looking content has a declared /Length that does not match the recovered stream body. Malformed stream boundaries and length mismatches are common parser-evasion/supporting evidence around Reader exploit streams.
  • 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
  • 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://testset.com In PDF document text
    • http://www.xfa.org/schema/xfa-locale-set/2.1/In PDF document text
    • http://ns.adobe.com/xdp/In PDF document text
    • http://www.xfa.org/schema/xci/1.0/In PDF document text
    • http://www.xfa.org/schema/xfa-data/1.0/In PDF document text

Extracted artifacts 5

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_file_obj0041.bin pdf-embedded-file PDF EmbeddedFile object 41 at offset 0xEB3 85 bytes
SHA-256: c06dcd026a7ea0536b63e07ce688691b585339a3ab7ff59065e546b56308c7bb
embedded_file_obj0042.bin pdf-embedded-file PDF EmbeddedFile object 42 at offset 0xF65 1029 bytes
SHA-256: dda0835df994b8be920f715db36452f6cee7bb42bbc9c897f878a7b298ba8e91
embedded_file_obj99999.bin pdf-embedded-file PDF EmbeddedFile object 99999 at offset 0x1181 21719 bytes
SHA-256: 3abf954250bb6e0df3243061811c74f0fc00c8fae4dec5d456c1ffb59440a986
embedded_file_obj0044.bin pdf-embedded-file PDF EmbeddedFile object 44 at offset 0x2864 144 bytes
SHA-256: 3dd68f00f4fcb366a2a3a17c65cb2626eeddf5ea5713302d374310561d810169
embedded_file_obj0045.bin pdf-embedded-file PDF EmbeddedFile object 45 at offset 0x2911 77 bytes
SHA-256: 10c03f88a5f0a0833dc5b2c8ac295b3a3c6f65e23889eb8cc1dc6fe29bf7f275

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