cbcvebase.
CVE-2015-2521
published 2015-09-09

CVE-2015-2521: Microsoft Excel 2007 SP3, Excel 2010 SP2, Office Compatibility Pack SP3, and Excel Viewer allow remote attackers to execute arbitrary code via a crafted Office…

PriorityP266critical9.3CVSS 2.0
AVNACMAuNCCICAC
EXPLOIT
EPSS
27.69%
97.9th percentile
Microsoft Excel 2007 SP3, Excel 2010 SP2, Office Compatibility Pack SP3, and Excel Viewer allow remote attackers to execute arbitrary code via a crafted Office document, aka "Microsoft Office Memory Corruption Vulnerability."

Affected

2 ranges
VendorProductVersion rangeFixed in
microsoftexcel
microsoftexcel

Detection & IOCsextracted from sources · hover to see the quote

urlhttps://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/38216.zip
filename1516065514_crash.xls
filename1516065514_min.xls
  • The malicious .xls file triggers a type confusion via a crafted OLESSDirectoryEntry.CreateTime field. The one-bit delta from the original file occurs at file offset 0x49E8 — monitor for XLS files with anomalous OLE Structured Storage directory entry CreateTime values.
  • Exploitation results in EIP corruption to 0xfffffffc via a corrupted function pointer dereference in Excel!Ordinal40. A crash at EIP=0xfffffffc in Excel.exe (version 12.0.6718.5000) processing an XLS file is a strong exploitation indicator.
  • The vulnerability involves an out-of-bounds read at offset 0x3F0 into a heap allocation of only 0x1B0 bytes, consistent with a type confusion. Heap page fault at eax+0x3F0 where the allocation size is 0x1B0 in Excel!Ordinal40 is a detection signal.
  • Affected Excel.exe version is 12.0.6718.5000 and MSO.dll version is 12.0.6721.5000 (Office 2007 SP3). Use version-based detection to identify unpatched installations.
  • ·The crash and exploitation path were only confirmed in Office 2007 with the Microsoft Office File Validation Add-In disabled. The bug did not reproduce in Office 2010 or 2013, limiting the scope of detection to Office 2007 SP3 targets.
  • ·Application Verifier must be enabled to observe the root-cause crash (heap out-of-bounds access); without it, only the downstream EIP corruption is visible. Production detections should not rely on Application Verifier being present.
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