PDF malware analysis — malicious · da09a57a17444166

MALICIOUS

PDF

7.7 KB

MD5: a945df50af295c124324053b5b483295 SHA-1: 15f0bcb4573c82bd0826b5193e035abc189c48cb SHA-256: da09a57a174441660c67b1e3d624e589b8399dffbccab1dd572ab40c4be82855

226 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1140 Deobfuscate/Decode Files or Information

The PDF contains obfuscated JavaScript, identified by multiple heuristics including 'PDF_JS_OBFUSCATED_DROPPER'. This script is designed to deobfuscate and execute further stages, likely downloading a second-stage payload. ClamAV detections 'Pdf.Exploit.Agent-36086' on both the original PDF and extracted artifacts confirm its malicious nature. The primary attack pattern involves leveraging embedded JavaScript within a PDF to initiate a multi-stage infection chain.

Heuristics 8

ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
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.

Filename	Kind	Source	Size
`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` `d686c3ecf5b4a530a9a4106d309b9ce32558ed5fbafa0593f524024439187583`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1997	1884 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`deobfuscated.js` `ac75ec98c63fb2b5e361476dc9652c5defee6ffccdeb9ab60186552dcf7d87ab`	deobfuscated-js	PDF JavaScript deobfuscation pass	44783 bytes
Detection ClamAV: Pdf.Exploit.Agent-36086 Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s).

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