Malicious PDF — malware analysis report

Static analysis result for SHA-256 ac1fd1fe9ad6ac00…

MALICIOUS

PDF

8.0 KB
MD5: 0e0c0bb8a7c19666df9cdbc1a55b646f SHA-1: b52e24407795445e00b6129b3c234becaccf9eef SHA-256: ac1fd1fe9ad6ac006901775f58fbae74a65d9f6c012980d34a626ac7597ad112
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF contains obfuscated JavaScript, identified as a high-severity heuristic for a "PDF_JS_OBFUSCATED_DROPPER". This script is designed to download and execute a second-stage payload. The ClamAV detection further confirms its malicious nature. The presence of multiple JavaScript streams and the use of unescape() point to a multi-stage attack.

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER
    PDF JavaScript shows 3 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, incremental_eval_build, repeated_pluginschk. This is strongly consistent with pre-2011 Adobe Reader PDF droppers — OpenAction JS reads encoded data from annotation subjects, decodes it through one or more hex / base-N loops, and invokes eval indirectly (method name built one character at a time). The actual CVE is hidden in the final decoded layer and is not visible via static analysis.
  • 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.
  • syncAnnotScan annotation-staging primitive low PDF_FOXIT_SYNCANNOTSCAN
    PDF JavaScript calls syncAnnotScan() — a no-op annotation-enumeration primitive used by exploit-kit JavaScript to stage payload reads from annotation /Subject fields before eval(). Not a vulnerable sink itself; rarely seen in legitimate PDFs. (matched in decompressed 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
f9b4659beaf681d266cfb5046d495e7b144d406eff72e71ecd4d1451ae25ca11
pdf-javascript-stream PDF /JS object 6 at offset 0x143 481 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
legacy_pdfkit_stage_000.js
f85eab03e6bf4f2a43befbe7b9d375ef6c21116b8cf93a8edcc58617b00588a5
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x1AA9 1715 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
deobfuscated.js
62fbb6b882cdce895940287633bcc8dcdd61e78bc7a425d11b3ba0a3c80f7325
deobfuscated-js PDF JavaScript deobfuscation pass 21162 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s).