Ramnit PDF malware analysis — malicious · a5383da80e062df5

MALICIOUS

PDF

111.7 KB

MD5: aa7ad55f9706e492b2a31389e971edd8 SHA-1: 9429681c479f470458dd79f3945686d3c266a742 SHA-256: a5383da80e062df52f51bbe0594f8c5394a3764ce88baec5d943e26d88f68404

212 Risk Score

Malware Insights

Ramnit · confidence 95%

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The PDF contains an embedded VBScript that is designed to reconstruct and execute a PE payload. The VBScript uses 'Scripting.FileSystemObject' and 'WScript.Shell' to write the payload to disk as 'svchost.exe' and then execute it. This behavior is consistent with Ramnit family malware, which often uses similar dropper mechanisms. The ML classifier also strongly indicated maliciousness.

Machine Learning

Nyx PDF Classifier malicious score 0.9695

Heuristics 5

VBScript in PDF stream reconstructs and runs a PE payload critical PDF_VBS_HEX_PE_DROPPER

PDF stream contains an HTML/VBScript block that decodes a long hex string into a Windows executable and runs it via WScript.Shell. This is an embedded dropper payload, not ordinary PDF JavaScript.
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.
Embedded script payload in PDF stream high PDF_EMBEDDED_SCRIPT_PAYLOAD

PDF stream bytes contain script execution markers such as ActiveXObject/CreateObject, WScript.Shell, PowerShell, or shell-exec primitives. This is stronger than ordinary PDF JavaScript because it indicates a staged external script payload hidden in stream bytes.
Suspicious extracted artifact medium 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.
PDF paints image(s) but contains no text operators info PDF_IMAGE_ONLY_LURE

PDF has 1 image XObject(s) and the content stream contains no text-emitting operators (BT/ET, Tj, TJ, ', ") in either raw bytes or decompressed streams — this is the screenshot-as-PDF pattern used to bypass text-based scanners and to deliver instructions purely through rendered pixels. It is informational unless paired with invisible links or risky URI context.

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`embedded_vbs_dropper_000004d5.vbs` `50b36b292c4a29f5f0d9642bb1487d597e7f817cb538628ff0d791b00e4fac65`	pdf-embedded-script	PDF raw bytes VBScript dropper at offset 0x4D5	113122 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 1 long base64-like blob(s).
`svchost.exe` `fd6c69c345f1e32924f0a5bb7393e191b393a78d58e2c6413b03ced7482f2320`	embedded-pe	Decoded PE from PDF VBScript dropper at offset 0x4D5	56320 bytes
Detection ClamAV: Win.Trojan.Ramnit-9775455-0 Obfuscation or payload: likely Carved artifact entropy is 7.89, consistent with packed or encrypted content.

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