Advisories

verify-usb before 1.4.9 Symlink Directory Traversal Code Execution

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severity
high
date
Affecting
  • openssl_encrypt >= 0, < 1.4.9

CWE
  • CWE-59 Improper Link Resolution Before File Access ('Link Following')
CVSS
8.7
CVSS V4 Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Description
openssl-encrypt (pip package) before 1.4.9 contains a symlink-following flaw in its verify-usb v2 added-file allowlist scan. The scan enumerated the drive with rglob(), which in CPython does not descend into symlinked directories and treats the symlink as an ordinary directory, while O_NOFOLLOW on the hash side binds only the final path component. An evil-maid attacker with physical access to the removable drive could replace a tool-tree directory with a symlink to a copy containing byte-identical files plus a planted __pycache__/*.pyc file (which CPython loads in preference to recompiling the clean .py). The planted file is never enumerated, added_files stays 0, and verify-usb reports PASSED, resulting in code execution when the victim runs the portable install. Fixed in 1.4.9 (affects both 1.4.x and 1.5.x lines).

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