Malicious PDF — malware analysis report

Static analysis result for SHA-256 b1c06dce81e612df…

MALICIOUS

PDF

72.4 KB Created: 2021-09-26 15:53:13 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: e27f1b9bba5acf3fcc19c10366995577 SHA-1: 39198c083361ef4b6a91fb721200bb383441a51c SHA-256: b1c06dce81e612dff4e1b3dd068360bd31218319a0a783b1a0eb0b536e2b87bc
204 Risk Score

Malware Insights

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

The sample is a PDF document containing embedded JavaScript and numerous links. Several heuristics indicate that these links are part of a link farm, with many pointing to compromised WordPress upload directories or disposable hosting. The embedded JavaScript and the nature of the links suggest an attempt to redirect the user to a malicious second-stage payload, likely a phishing or malware download page. The ClamAV detection and ML classifier further support its malicious nature.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9976

Heuristics 8

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • PDF link to algorithmically-generated URL high PDF_RANDOM_URL_LINK
    PDF contains a clickable HTTP(S) link whose host looks algorithmically generated (pronounceable-random labels) and whose path/query carries a long high-entropy token. This is the randomized-redirector pattern of malspam phishing lures — the visible document is only a prompt — not a PDF parser vulnerability.
  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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.
  • 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.
  • 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 http://sial.pl/galeria/file/50600529381.pdf
    • http://cyc.cz/pictures/clanky/files/73339984011.pdf
    • https://maconlux.lu/userfiles/files/21828435585.pdf
    • https://devisme.maxtis.com/userfiles/file/21587614685.pdf
    • https://sfasg.jp/js/ckfinder/userfiles/files/78003603861.pdf
    • https://www.grecosalesinternational.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613159051f49c---73385907775.pdf
    • https://assofmt.org/ckfinder/userfiles/files/14110302127.pdf
    • https://tenderdiary.com/ckfinder/userfiles/files/fubinofi.pdf
    • https://vinniescustoms.com/userfiles/files/vuvojuwijuwutaromu.pdf
    • https://gsm.company/ckfinder/userfiles/files/rewatopexaxumoguvilezava.pdf
    • http://wib24-admin.de/uploads/file/63189020566.pdf
    • https://m3nan973ru5-pa571.com/contents/files/47986868212.pdf
    • https://mygenius.ru/admin/ckfinder/userfiles/files/bamopazik.pdf
    • https://keralatemples.info/ckfinder/userfiles/files/96892649937.pdf
    • https://mimpishio2bet.net/contents/files/tapel.pdf
    • http://ambulatorioveterinariopisillibertozzi.eu/userfiles/files/nurepetofo.pdf
    • http://2safe4u.cz/UserFiles/File/pazarerog.pdf
    • http://alternativefitness.com.au/wp-content/plugins/formcraft/file-upload/server/content/files/1614f8b0413687---68885642406.pdf
    • http://tencanpowder.com/d/files/wefogidumufunomeb.pdf
    • http://sziszolg.hu/editor_up/xipekaremogadezixuwele.pdf
    • http://aprt1day.ru/file/wigesapem.pdf
    • https://serka.com/serka/upload/files/55577244117.pdf
    • https://www.democratum.com/wp-content/plugins/super-forms/uploads/php/files/95e7a52ec102689f67de958130aabb51/bemevik.pdf
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/LPIa9PGmDLg/uplcv?utm_term=moving+apps+to+external+storage
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://dejavu.sourceforge.net
    • http://dejavu.sourceforge.net/wiki/index.php/License

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000b5eb.bin
a6067fc6f453d6ca3498c9417b9fc127e9020acb23a1a4a84aeb4ef7cbdc6df4
pdf-font-stream PDF embedded font (sfnt) at offset 0xB5EB 17668 bytes
font_01_sfnt_off0000e324.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
pdf-font-stream PDF embedded font (sfnt) at offset 0xE324 16792 bytes
font_02_sfnt_off0000fb3b.bin
e9126696ab83759510ae2b351769df855a41c796026823878939e64160ffe69b
pdf-font-stream PDF embedded font (sfnt) at offset 0xFB3B 10588 bytes