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fix(OfficeUtils): strengthen ZipSlip path traversal protection in ZIP extraction #117

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fix(OfficeUtils): strengthen ZipSlip path traversal protection in ZIP extraction #117

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50 changes: 45 additions & 5 deletions OfficeUtils/src/ZipUtilsCP.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -288,15 +288,55 @@ namespace ZLibZipUtils
err = unzOpenCurrentFilePassword(uf, password);

//-------------------------------------------------------------------------------------------------

// ZipSlip protection: verify the resolved output path stays within unzip_dir
if (unzip_dir)
{
const std::wstring wsFilePath{NSSystemPath::ShortenPath(filenameW)};
// Normalize the filename to resolve any ../ or ./ components
const std::wstring wsNormalizedFilename = NSSystemPath::ShortenPath(filenameW);

if (wsFilePath.size() > 3 && L'.' == wsFilePath[0] && L'.' == wsFilePath[1] && L'/' == wsFilePath[2])
// Reject if normalization produced an empty path
if (wsNormalizedFilename.empty())
return UNZ_INTERNALERROR;
}

// Reject absolute paths in the archive entry itself
#if defined(_WIN32) || defined (_WIN64)
bool bIsAbsolute = false;
// Drive letter: C:\ or C:/
if (wsNormalizedFilename.size() >= 2 &&
wsNormalizedFilename[1] == L':' &&
(wsNormalizedFilename[0] >= L'A' && wsNormalizedFilename[0] <= L'Z' ||
wsNormalizedFilename[0] >= L'a' && wsNormalizedFilename[0] <= L'z'))
bIsAbsolute = true;
// UNC path: \\server\share
if (wsNormalizedFilename.size() >= 2 &&
wsNormalizedFilename[0] == L'\\' && wsNormalizedFilename[1] == L'\\')
bIsAbsolute = true;
if (bIsAbsolute)
return UNZ_INTERNALERROR;
#else
// Unix-like: absolute path starting with /
if (!wsNormalizedFilename.empty() && wsNormalizedFilename[0] == L'/')
return UNZ_INTERNALERROR;
#endif

// Build the normalized output path and verify containment within unzip_dir
std::wstring wsNormalizedOutput = NSSystemPath::ShortenPath(output);
std::wstring wsNormalizedDir = NSSystemPath::ShortenPath(unzip_dir);

// Ensure directory ends with separator for proper prefix matching
if (!wsNormalizedDir.empty() &&
wsNormalizedDir.back() != L'/' && wsNormalizedDir.back() != L'\\')
{
wsNormalizedDir += FILE_SEPARATOR_STR;
}

// Verify the output path starts with the extraction directory prefix
if (wsNormalizedOutput.size() < wsNormalizedDir.size() ||
wsNormalizedOutput.substr(0, wsNormalizedDir.size()) != wsNormalizedDir)
{
return UNZ_INTERNALERROR;
}
}
//-------------------------------------------------------------------------------------------------
NSFile::CFileBinary oFile;
FILE *fout = NULL;
Expand Down Expand Up @@ -480,7 +520,7 @@ namespace ZLibZipUtils

std::wstring filenameW = codepage_issue_fixFromOEM(filename_inzip);

//TODO is there a need to reduce everything to the bottom???
//TODO is there a need to reduce everything to the bottom???
if (wcscmp(filename, filenameW.c_str()) == 0)
return true;

Expand Down
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