RTF / .DOC malware analysis — malicious · 52a55642974b0f7d

MALICIOUS

RTF / .DOC

1.59 MB First seen: 2022-03-29

MD5: 1a6cee64066011b7dbd83a3190c99000 SHA-1: 16cc87858a68477c2774df1735b7bc34afada5f4 SHA-256: 52a55642974b0f7de09eb1cb6fce4521654398b104da8bc951a69a7c969ebf82

220 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell T1105 Ingress Tool Transfer

The file is an RTF document containing OLE object data, specifically related to Equation Editor. Critical heuristics indicate the exploitation of CVE-2017-11882, a known vulnerability in Microsoft Office's Equation Editor component. This vulnerability is typically used to execute arbitrary code, often to download and run a secondary payload. The presence of large hex-encoded data blocks within the OLE object further suggests the hiding of malicious content.

Heuristics 5

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.
Split hex Equation Editor ProgID + OLE object critical 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.
\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.
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~1660KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00001dce.bin` `c2aa42dcf6720ebbf51058d70943da7a5501e978ebfc004fd291a476672fe655`	rtf-objdata-decoded	RTF \objdata at offset 0x1DCE	830065 bytes

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