From 9217b76b16938066b3d70509bcd5d766234a5afc Mon Sep 17 00:00:00 2001 From: TrellixVulnTeam Date: Wed, 16 Nov 2022 13:01:17 +0000 Subject: [PATCH] Adding tarfile member sanitization to extractall() --- b1/chapter8/l31_tarfile_extractall.py | 21 ++++++++++++++++++- b1/chapter8/l32_tarfile_extractall_members.py | 21 ++++++++++++++++++- 2 files changed, 40 insertions(+), 2 deletions(-) diff --git a/b1/chapter8/l31_tarfile_extractall.py b/b1/chapter8/l31_tarfile_extractall.py index 506c726..25e504f 100644 --- a/b1/chapter8/l31_tarfile_extractall.py +++ b/b1/chapter8/l31_tarfile_extractall.py @@ -3,5 +3,24 @@ os.mkdir('outdir') with tarfile.open('example.tar', 'r') as t: - t.extractall('outdir') + def is_within_directory(directory, target): + + abs_directory = os.path.abspath(directory) + abs_target = os.path.abspath(target) + + prefix = os.path.commonprefix([abs_directory, abs_target]) + + return prefix == abs_directory + + def safe_extract(tar, path=".", members=None, *, numeric_owner=False): + + for member in tar.getmembers(): + member_path = os.path.join(path, member.name) + if not is_within_directory(path, member_path): + raise Exception("Attempted Path Traversal in Tar File") + + tar.extractall(path, members, numeric_owner=numeric_owner) + + + safe_extract(t, "outdir") print(os.listdir('outdir')) diff --git a/b1/chapter8/l32_tarfile_extractall_members.py b/b1/chapter8/l32_tarfile_extractall_members.py index 48a3318..a30876b 100644 --- a/b1/chapter8/l32_tarfile_extractall_members.py +++ b/b1/chapter8/l32_tarfile_extractall_members.py @@ -3,5 +3,24 @@ os.mkdir('outdir') with tarfile.open('example.tar', 'r') as t: - t.extractall('outdir', members=[t.getmember('README.txt')],) + def is_within_directory(directory, target): + + abs_directory = os.path.abspath(directory) + abs_target = os.path.abspath(target) + + prefix = os.path.commonprefix([abs_directory, abs_target]) + + return prefix == abs_directory + + def safe_extract(tar, path=".", members=None, *, numeric_owner=False): + + for member in tar.getmembers(): + member_path = os.path.join(path, member.name) + if not is_within_directory(path, member_path): + raise Exception("Attempted Path Traversal in Tar File") + + tar.extractall(path, members, numeric_owner=numeric_owner) + + + safe_extract(t, "outdir", members=[t.getmember("README.txt")]) print(os.listdir('outdir'))