Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 5d3649849d77e71c…

MALICIOUS

RTF / .DOC

2.24 MB
MD5: a2e5035ced49c0e6b411983afb9f5a86 SHA-1: 08665f878000419f88b32c2b9321e7f421713be1 SHA-256: 5d3649849d77e71c5bf614c7ae6442f4a70ece48ddf712155ee1c5fbd027b135
180 Risk Score

Malware Insights

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

The RTF file contains multiple indicators of malicious activity, including embedded OLE objects and specific heuristics pointing to the CVE-2017-11882 Equation Editor vulnerability. The presence of \objupdate further suggests an attempt to force OLE activation. The decoded object data contains what appears to be VBScript code, 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
b4b3d67d409802b32032e2ade627586d0e09237c34120aae8fb53ac241bdb70a		 rtf-objdata-decoded RTF \objdata at offset 0x1202 27708 bytes
objdata_01_off0001d285.bin
05fc6d2b0a81484fefcb6cc6d4891013e53501190027c21cdd96bf0ea0957523		 rtf-objdata-decoded RTF \objdata at offset 0x1D285 478713 bytes

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