Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b1cb28ab9ab7f679…

MALICIOUS

RTF / .DOC

2.24 MB
MD5: 1d936ec0a10ce7afbc7354721bcfbfba SHA-1: 6c20e5c905de3aa09b051a615b84bf16c87c32e9 SHA-256: b1cb28ab9ab7f679ee1722417673000d39cb6afcb3928ccd69df2e095376b9a7
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains multiple indicators of exploitation, specifically related to CVE-2017-11882 through the Equation Editor. The presence of OLE object data and the ".objupdate" directive strongly suggest that the embedded Equation Editor object is designed to be activated, leading to arbitrary code execution. The decoded object data contains what appears to be obfuscated VBScript, likely intended to download and execute a second-stage payload.

Heuristics 5

  • 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.
  • 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.
  • 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.

FilenameKindSourceSize
objdata_00_off00001202.bin
5d6297752398571524909dadea4e4f2e823b2a0a0aa1c617842245491127ba1b		 rtf-objdata-decoded RTF \objdata at offset 0x1202 27240 bytes
objdata_01_off0001cedd.bin
420dd98e97f2838b69fef2f6d85eff987f569ee4001ae1d6183f751f72b4b727		 rtf-objdata-decoded RTF \objdata at offset 0x1CEDD 480330 bytes

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