PDF malware analysis — malicious · 545404e6db7e0083

MALICIOUS

PDF

7.7 KB

MD5: 353e546280bb445c95e531fa11b01175 SHA-1: f959b7564236ed940a3279582e5c645754825f8e SHA-256: 545404e6db7e00837c369ba6a238f1ca7bf9c547e344efa5e61d8d87ca05ba09

166 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1566.001 Spearphishing Attachment T1140 Deobfuscate/Decode Files or Information

The PDF contains obfuscated JavaScript, identified as a multi-stage dropper. The script employs anti-analysis techniques such as repeated app.plugIns.length checks and incremental method name building. It is designed to decode and execute a second-stage payload, likely from an external source, as indicated by the 'unescape()' call and the presence of deobfuscated JavaScript streams. The ClamAV detection 'Pdf.Exploit.Agent-36086' further confirms its malicious nature.

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.

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` `ab4d55de850db7f23c5e44dc1675dd85071ec44e7dd08bddb22358cf1a24aecf`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x19A4	1790 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`deobfuscated.js` `3523b300ee7fafa9ad748353d2a9107196dcc563085b07b6f0426159497a22fa`	deobfuscated-js	PDF JavaScript deobfuscation pass	22959 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).

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