Malicious PDF — malware analysis report

Static analysis result for SHA-256 89155db93b7fe5f8…

MALICIOUS

PDF

118.5 KB
MD5: 838119f322992a4c20d8b645d7d1236b SHA-1: 23de18064477d20eb607889ed583374b44f855c9 SHA-256: 89155db93b7fe5f83473de1b4dcc61ba9724fb3f90212903da6f3bd7fcaa90a5
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment

The sample is a PDF file that contains embedded JavaScript, as indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_JS_LARGE_COMMENT_PADDED_EVAL'. The presence of 'PDF_EVAL' and 'PDF_FROMCHARCODE' suggests the JavaScript is obfuscated and designed to execute arbitrary code. ClamAV detection as 'Pdf.Exploit.Agent-36086' further confirms its malicious nature. The primary attack pattern involves exploiting PDF vulnerabilities to run this script, which is likely a stager for downloading and executing further malicious content.

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Large comment-padded JavaScript eval stager high PDF_JS_LARGE_COMMENT_PADDED_EVAL
    PDF JavaScript contains a very large stream padded with long random-looking block comments around String.fromCharCode and eval. This is an exploit-kit obfuscation shape used to bury a decoder and recovered stage inside noise, not normal PDF form automation.
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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.
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
1bb57568959a20c147a2a535dfe0129e115248f01ddb464b8fe4f861945341f0
pdf-javascript-stream PDF /JS object 6 at offset 0x143 626911 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 42 long base64-like blob(s).