RTF malware analysis — malicious · a9894d3da0c489db

MALICIOUS

RTF

1.77 MB First seen: 2021-07-13

MD5: fba331acf84ce1bcac8b124c54a326e3 SHA-1: d8a7f43bd194435c6b5e216060c189a91a6aedd6 SHA-256: a9894d3da0c489db83a3579db0fbb6f5f76a2ef6c2d6177b8572b989376533ab

220 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains embedded OLE objects, specifically triggering heuristics related to Equation Editor and CVE-2017-11882. The presence of shellcode command strings within an extracted artifact further indicates the execution of a malicious payload. The exploit likely serves as a delivery mechanism for a secondary stage, commonly seen in phishing attacks.

Heuristics 6

Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR

RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED

RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
\objupdate forces OLE activation high RTF_OBJUPDATE

RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
Suspicious extracted artifact high 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.
OLE object data medium RTF_OBJDATA

RTF contains 2 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000011e1.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x11E1	53799 bytes
SHA-256: `c687a6b62e08a3fbf4d30a27136f26525c62732e2dd3ed061bd4fd27fd3bbc82`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): WScript.ScriptName, WScript.Quit(), Cmd = strActivationID(""" ypoc c/ dmc") & sKeys & WScript.ScriptName & """ """ & lValue & """ /Y"
`objdata_01_off0002fc81.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x2FC81	453383 bytes
SHA-256: `e1f744f201031a94b7338c99efa7dc221d6af19e0163291dabfeddbdf7cb992f`

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