Malicious PDF — malware analysis report

Static analysis result for SHA-256 557966cbc6bc2c09…

MALICIOUS

PDF

86.7 KB Created: 2021-10-08 04:23:24 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-24
MD5: 0dae131dc2392af4f29b3581410e6acb SHA-1: 531f465ee8ec547821f131b58ff602fedfc0fd50 SHA-256: 557966cbc6bc2c09cf06b5004cc2705993c72cbfb9ece6a1e00a59a6d72d4454
146 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains malformed streams and multiple external URIs, indicating malicious intent. The ML classifier and ClamAV detection strongly suggest this is a phishing or trojan delivery mechanism. The presence of embedded URLs points towards an attempt to redirect the user to malicious sites, likely as part of a spearphishing campaign.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9992

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://catamma.ru/uplcv?utm_term=that+was+the+reason PDF link annotation
    • http://vibratingsieve.com/d/files/kududikeg.pdfIn PDF document text
    • https://www.hkha.org/ckfinder/userfiles/files/rekanefelulakezebivobez.pdfIn PDF document text
    • http://www.cheapmotorcycleinsurancepa.com/wp-content/plugins/super-forms/uploads/php/files/5787603eaf1b09863745932a5c3a7bb3/gipimerozujopogibet.pdfIn PDF document text
    • http://www.salpasafarit.fi/tiedostot/files/68839428519.pdfIn PDF document text
    • https://stephankeppel.com/userfiles/file/bokugidetamonaxafu.pdfIn PDF document text
    • http://brianhaymore.com/images/e/file/rorujasotasuvamimubapade.pdfIn PDF document text
    • http://mebco.ru/images/file/wuxoguzegosexam.pdfIn PDF document text
    • http://www.egavilanes.com/ckfinder/userfiles/files/tusebad.pdfIn PDF document text
    • https://springkasteelhuren.be/userfiles/file/muloximipusedubiritod.pdfIn PDF document text
    • http://scsychem.com/upload/files/83002124973.pdfIn PDF document text
    • http://lixupeng.com/uploads/files/20651562744.pdfIn PDF document text
    • http://hengtongrongshang.com/jingkelun/userfiles/files/20210906062127.pdfIn PDF document text
    • http://speaklifeiamgreatness.com/files/files/42409030282.pdfIn PDF document text
    • http://rkmaster.ru/uploads/files/tenavojapaduniwebonopimag.pdfIn PDF document text
    • http://itcck.org/upload/editor/file/35270560745.pdfIn PDF document text
    • http://smolninskayahotel.com/userfiles/file/taruru.pdfIn PDF document text
    • http://mbeautyconcept.com/upload/content_images/file/lolunasitibenoxumipises.pdfIn PDF document text
    • http://soft-pro.hr/upload/datoteke/18967392483.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_off0000ea9c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEA9C 20432 bytes
SHA-256: e8353439ab2fae7beb75a444547a2f8a15124a956588d5d0f452146a8e069cb1
font_01_sfnt_off00011f78.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11F78 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0001378f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1378F 10116 bytes
SHA-256: 17490f2307c07544bbea04d98e1ed82eab592f47c1c1e6f7e49debac3d549545

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