Malicious PDF — malware analysis report

Static analysis result for SHA-256 6b57ca53b53b32b9…

MALICIOUS

PDF

80.0 KB Created: 2021-10-05 11:45:54 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-24
MD5: 328a640e49a32cad35c5c9d87a12695f SHA-1: 913dc4422f42ff1b21291facae16b094ea8bc4f9 SHA-256: 6b57ca53b53b32b9fb3f0bbbe4786b0fffbcf139250f41ae6a7bd71f8bcc8360
146 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is a PDF file flagged as malicious by ClamAV and an ML classifier, exhibiting malformed streams indicative of exploit code. It contains a large number of embedded URLs, many of which are on disposable domains, suggesting a phishing or link-farming scheme. The presence of external URIs and the overall structure point towards an attempt to redirect users to malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9992

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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.
  • Small PDF is a non-clustered link farm on disposable hosting medium PDF_SEO_DISPOSABLE_LINK_FARM
    Small PDF contains many clickable external PDF links spread thin across many distinct hosts (no single dominant host), corroborated by a utm_term SEO-redirector link and/or links parked on free/disposable content hosts. This is the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains, rather than a normal document citation pattern. The PDF itself carries no exploit — the risk is the linked destinations.
  • External URI info PDF_URI
    PDF contains an external URL action
  • 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 https://wastran.ru/uplcv?utm_term=calories+in+white+wine PDF link annotation
    • http://biosurfest.com/userfiles/files/95813901473.pdfIn PDF document text
    • https://olterus.org/contents/files/nukarepusajifivewidi.pdfIn PDF document text
    • http://kaus21.com/userData/board/file/wutuvejozekazo.pdfIn PDF document text
    • https://12shio3.com/contents/files/58796226955.pdfIn PDF document text
    • http://fertilityupdates.com/userfiles/files/makigufalo.pdfIn PDF document text
    • http://picart-personal.pl/fckupload/upload/file/89340331377.pdfIn PDF document text
    • https://hattoco.vn/images/ckeditor/files/33867777890.pdfIn PDF document text
    • https://ctners.com/ckfinder/userfiles/files/gexisezagetirefudog.pdfIn PDF document text
    • http://madinaboys.com/easydo%20v2.00/files/uploads/16746913497.pdfIn PDF document text
    • http://spartaksedlec.cz/spartaksedlec/userfiles/file/56859619776.pdfIn PDF document text
    • http://bjxbw.cn/userfiles/file/jedikumeposubelakip.pdfIn PDF document text
    • https://institut-arabe.org/ckfinder/userfiles/files/xibiras.pdfIn PDF document text
    • https://martas.vodrsport.cz/uploads/files/37936489672.pdfIn PDF document text
    • http://scard.vn/app/webroot/uploads/files/60821949454.pdfIn PDF document text
    • https://telorgabus.com/contents/files/fenekezaperedesini.pdfIn PDF document text
    • http://firsttimehomebuyerstudy.com/images/file/xakonerutumimulekujuv.pdfIn PDF document text
    • https://jesssmithtri.com/jesssmith/ckfinder/userfiles/files/lovoxafasegifabilubajala.pdfIn PDF document text
    • http://vekosgroup.ru/userfiles/file/nuparabusezorof.pdfIn PDF document text
    • http://virus-safe-zone.com/ckupload/files/25208686785.pdfIn PDF document text
    • https://posh.hr/files/53213870190.pdfIn PDF document text
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/xap/1.0/rights/In PDF document text
    • http://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000d0ec.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD0EC 19576 bytes
SHA-256: 88394db526da02fb1e01599b1c6eee68ae3825d17f1b774ceb5e6c06cfdf7943
font_01_sfnt_off000103e3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x103E3 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00011bfa.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11BFA 10324 bytes
SHA-256: f5eb4ff79fba147c4e80bd6506253ff2d30d21e0193aec8fe465e4b51b5df017

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