Malicious PDF — malware analysis report

Static analysis result for SHA-256 5db86f3fba8fe7dc…

MALICIOUS

PDF

43.0 KB Created: 2012-12-22 19:35:24 Authoring application: nprqftdfpyybbps (via nqxbljmwhywxctn) First seen: 2013-01-03
MD5: 4a092cf83cf5a9f571819eabcb78fd27 SHA-1: 5220df6e077143dae280eaf462114427eae21e53 SHA-256: 5db86f3fba8fe7dc992554a2f6055d6e976d32504d53d217c91b39caf8c621c1
70 Risk Score

Malware Insights

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

The sample is a PDF file exhibiting characteristics of exploitation, including a malformed active-content stream and an embedded file. The ML classifier strongly indicates maliciousness. The presence of an embedded file suggests a secondary payload is likely delivered, and the exploitation of PDF vulnerabilities points to client execution.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9523

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
  • 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.
  • 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://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-template/2.2/In PDF document text
    • http://www.xfa.org/schema/xfa-data/1.0/In PDF document text
    • http://ns.adobe.com/xfdf/In PDF document text
    • http://www.xfa.org/schema/xfa-form/2.8/In PDF document text

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_file_obj0016.bin pdf-embedded-file PDF EmbeddedFile object 16 at offset 0x179C 10096 bytes
SHA-256: a3275e7333b0bfbf31b24479bac9819bf6308c99271857011d7a3e1f4ca700ac

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