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Improve Screenshot Detection by Modifying capture-screenshot.yml #1007

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Improve Screenshot Detection by Modifying capture-screenshot.yml #1007

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51bd126
Improve screenshot detection by modifying capture-screenshot.yml to i…
akh7177 Feb 24, 2025
4cd4879
Merge pull request #1 from akh7177/add-screenshot-rule
akh7177 Feb 24, 2025
52e3a3b
Refactor screenshot rule to remove duplication
akh7177 Feb 25, 2025
ea56ada
Modify test executable for screenshot capture
akh7177 Feb 26, 2025
d258016
Merge branch 'mandiant:master' into add-screenshot-rule
akh7177 Mar 11, 2025
bb5a21f
Improve screenshot detection by modifying capture-screenshot.yml to i…
akh7177 Mar 11, 2025
1d7527a
Merge branch 'mandiant:master' into add-screenshot-rule
akh7177 Mar 12, 2025
aaebf44
Improve screen-capture detection
akh7177 Mar 12, 2025
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49 changes: 49 additions & 0 deletions collection/screenshot/capture-screenshot.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ rule:
- [email protected]
- "@_re_fox"
- [email protected]
- "Abhyuday K Hegde"
scopes:
static: function
dynamic: span of calls
Expand All @@ -17,7 +18,10 @@ rule:
- BFB9B5391A13D0AFD787E87AB90F14F5:0x1314610A
- 7204e3efc2434012e13ca939db0d0b02:0x414070
- 50D5EE1CE2CA5E30C6B1019EE64EEEC2:0x406E07
- 333cf4a403f2dbd56e2509eb2f1d8922:0x140002180
- de5f2dd641b3e75eea6e4575b0ba4a48:0x140002180
features:
# Classic GDI Capture
- or:
- and:
- or:
Expand All @@ -43,3 +47,48 @@ rule:
- and:
- api: BitBlt
- api: System.Drawing.Graphics::CopyFromScreen

- and:
- or:
- api: "GetDC"
- and:
- api: "CreateDC"
- optional:
- string: "DISPLAY"
- or:
- and:
- api: "SelectObject"
- api: "DrawText"
- and:
- api: "CreateCompatibleDC"
- api: "CreateCompatibleBitmap"
- or:
- api: "BitBlt"
- api: "StretchBlt"
- api: "PrintWindow"
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some of this seems to be duplicated from above, right? would you please merge the logic where reasonable?

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Hello @williballenthin ,

I've tried to remove the duplicated parts of the code and committed the changes. Please let me know if further improvements are required.


# GDI+ Graphics API chain
- and:
- api: "GdipCreateBitmapFromScan0"
- api: "GdipGetImageGraphicsContext"
- api: "GdipGetDC"

# Direct GDI+ screen copy

- and:
- api: "Gdiplus::Graphics::FromHDC"
- api: "Gdiplus::Graphics::CopyFromScreen"
Comment on lines +63 to +64
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Should these be api or function-name features?

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Hello @mike-hunhoff !
According to my understanding, Gdiplus is not from a statically linked library right?


# DirectX method of screen capture
- and:
- or:
- api: "PrintWindow"
- api: "StretchBlt"
- and:
- api: "DwmGetDxSharedSurface"
- optional:
- string: "DXGI"
- or:
- api: "Direct3DCreate9"
- api: "IDirect3DDevice9::GetFrontBufferData"
Comment on lines +75 to +76
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Should these be api or function-name features?

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Over here too, Direct3DCreate 9 is a direct import of a dll file right?

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Furthermore, changing these features to function-name would require me to change the static scope of the rule to file. Would it not increase the number of false positives?

- string: "IDirect3DSurface9::GetDC"