PDF malware analysis — malicious · 8fa83c156e45c654

MALICIOUS

PDF

8.1 KB

MD5: fc2db6e1c28b7a3c28281851b0006406 SHA-1: 4c53530902f26f85163e50e64c0ce91bdc72f763 SHA-256: 8fa83c156e45c65407e1212b4a6be65d2b5d4f7983c91d2ba31d7c576936b458

194 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link

The PDF file contains obfuscated JavaScript that leverages the CVE-2007-5659 vulnerability (Collab.collectEmailInfo) to execute. The JavaScript is designed as a multi-stage dropper, indicated by the presence of multiple deobfuscated JavaScript files and heuristic firings like PDF_JS_OBFUSCATED_DROPPER. The primary function of the script is to download and execute a secondary payload from a remote source, although the specific URL is not directly extractable from the provided evidence.

Heuristics 8

Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659

PDF JavaScript calls Collab.collectEmailInfo — CVE-2007-5659 is a buffer overflow in Adobe Reader triggered by a long argument or heap-sprayed message field passed to Collab.collectEmailInfo(). Part of a series of Acrobat JS API exploits. (identified after JavaScript deobfuscation)
ClamAV: Pdf.Dropper.Agent-7282248-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Dropper.Agent-7282248-0
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, hex_dashed_payload, 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.
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)
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 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `9d5c7e01faed5b04e9ec11f1d98b73f0012c871beaf60e9f9d32ad6df00d46f7`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	550 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` `40173aaa7e8bd6f78735d6b8492b1037d9488867fbbf0ba6ebd8cbce46e8dfdc`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B52	1729 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_001.js` `4ae0e1330ddb7a85db6633dd0cb0400c9bc5918f63e4a2da5ddde59580120a48`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x359	5048 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `08e6ceec7eb894d141ac92894cdfa554d79e2be154393acb5d1da9d5f326301e`	deobfuscated-js	PDF JavaScript deobfuscation pass	24778 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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