RTF malware analysis — malicious · f6172d73ff4f0524

MALICIOUS

RTF

6.0 KB First seen: 2020-09-07

MD5: 6e6ccd2dfb3147dfaec8a285ff134a49 SHA-1: fefe342f00694b8c1fbf1cd4d41126e8a03aa82a SHA-256: f6172d73ff4f05242184ba7bf87cdce2f7c6733b15b81cf8a59e44e08e41e62d

220 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains an embedded OLE object that triggers CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. This vulnerability allows for the execution of arbitrary code, likely to download and run a second-stage payload. The presence of the objdata_00_off00000ce9.bin artifact further supports the exploitation of this vulnerability.

Heuristics 6

Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR

RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
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.
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 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00000ce9.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xCE9	1179 bytes
SHA-256: `1811920de1dc99c7091dcfdba57bf6c10f12a353be9efa21d7136cb136f2e91b`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis found candidate code region(s). Indicators: SC_GETPC_CALL

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