RTF malware analysis — malicious · 48a05e42214277f9

MALICIOUS

RTF

158.5 KB First seen: 2020-09-07

MD5: a16c9c7e48403e3e165115752fa4ceda SHA-1: 8568892da5659fd33a8380eafd3558c0618a70b5 SHA-256: 48a05e42214277f9a4fe66017f03cce54570e22aab74cc8aa7e0a66ec4d3d4d3

282 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object that exploits CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The heuristic firings indicate that this object is a decoded Equation Editor payload containing a PE file, strongly suggesting it acts as a dropper. ClamAV also identifies it as Rtf.Dropper.Agent-9610185-0, further supporting its role as a malware dropper.

Heuristics 7

Decoded Equation Editor payload + PE critical CVE likely RTF_EQUATION_EDITOR

RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED

RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
ClamAV: Rtf.Dropper.Agent-9610185-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Dropper.Agent-9610185-0
Automatically linked OLE object high RTF_OBJAUTLINK

RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
\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.
OLE object data medium RTF_OBJDATA

RTF contains 1 \objdata section(s) — embedded OLE objects
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000017d9.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x17D9	78002 bytes
SHA-256: `ac4c8fd8ab3c4d276d4384f224c52a0d6b4dc0fe20c70b7090d81af4b14f34c9`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.

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