Malicious RTF — malware analysis report

Static analysis result for SHA-256 16fc1ecc295f8d7d…

MALICIOUS

RTF

2.09 MB
MD5: bdacb3b17f31a06a8cfbedba2342bdf5 SHA-1: 9f6930782942ec4bedc162be334b97f861d24f75 SHA-256: 16fc1ecc295f8d7dba6647b9aeb8d538932910b24f3affe1853a82ab2c9d944a
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains an embedded OLE object with a split Equation Editor ProgID, strongly indicating exploitation of CVE-2017-11882. The ".objupdate" directive forces the activation of this embedded object, leading to the execution of the exploit. The decoded object data suggests an attempt to run a script, likely 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
1845ef988935924662433d07f966010128cc3c8c4da553430b33b824fe0dcee9		 rtf-objdata-decoded RTF \objdata at offset 0x1202 27277 bytes
objdata_01_off0001cf27.bin
53b9f303d393dc929d79a2b5c8f4ddab6c91c8bfe1e80e0ffc1a4d210ef1046d		 rtf-objdata-decoded RTF \objdata at offset 0x1CF27 362344 bytes

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