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Merge pull request #2888 from RasmusWL/python-tarslip-sanitizer

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Python: Improve tarslip sanitizer
This commit is contained in:
Taus
2020-03-24 12:59:20 +01:00
committed by GitHub
parent 4c9a6b73ee dcfc9a8796
commit fe00d1cbf4
3 changed files with 49 additions and 2 deletions
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14
python/ql/src/Security/CWE-022/TarSlip.ql
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@@ -121,9 +121,19 @@ class ExtractMembersSink extends TaintSink {
class TarFileInfoSanitizer extends Sanitizer {
TarFileInfoSanitizer() { this = "TarInfo sanitizer" }
/** The test `if <path_sanitizing_test>:` clears taint on its `false` edge. */
override predicate sanitizingEdge(TaintKind taint, PyEdgeRefinement test) {
path_sanitizing_test(test.getTest()) and
taint instanceof TarFileInfo
taint instanceof TarFileInfo and
clears_taint_on_false_edge(test.getTest(), test.getSense())
}
private predicate clears_taint_on_false_edge(ControlFlowNode test, boolean sense) {
path_sanitizing_test(test) and
sense = false
or
// handle `not` (also nested)
test.(UnaryExprNode).getNode().getOp() instanceof Not and
clears_taint_on_false_edge(test.(UnaryExprNode).getOperand(), sense.booleanNot())
}
}

7
python/ql/test/query-tests/Security/CWE-022/TarSlip.expected
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@@ -15,8 +15,15 @@ edges
| tarslip.py:34:14:34:16 | tarfile.open | tarslip.py:34:1:34:17 | tarfile.entry |
| tarslip.py:40:7:40:39 | tarfile.open | tarslip.py:41:24:41:26 | tarfile.open |
| tarslip.py:40:7:40:39 | tarfile.open | tarslip.py:41:24:41:26 | tarfile.open |
| tarslip.py:56:7:56:39 | tarfile.open | tarslip.py:57:14:57:16 | tarfile.open |
| tarslip.py:56:7:56:39 | tarfile.open | tarslip.py:57:14:57:16 | tarfile.open |
| tarslip.py:57:1:57:17 | tarfile.entry | tarslip.py:59:21:59:25 | tarfile.entry |
| tarslip.py:57:1:57:17 | tarfile.entry | tarslip.py:59:21:59:25 | tarfile.entry |
| tarslip.py:57:14:57:16 | tarfile.open | tarslip.py:57:1:57:17 | tarfile.entry |
| tarslip.py:57:14:57:16 | tarfile.open | tarslip.py:57:1:57:17 | tarfile.entry |
#select
| tarslip.py:13:1:13:3 | tar | tarslip.py:12:7:12:39 | tarfile.open | tarslip.py:13:1:13:3 | tarfile.open | Extraction of tarfile from $@ | tarslip.py:12:7:12:39 | Attribute() | a potentially untrusted source |
| tarslip.py:18:17:18:21 | entry | tarslip.py:16:7:16:39 | tarfile.open | tarslip.py:18:17:18:21 | tarfile.entry | Extraction of tarfile from $@ | tarslip.py:16:7:16:39 | Attribute() | a potentially untrusted source |
| tarslip.py:37:17:37:21 | entry | tarslip.py:33:7:33:39 | tarfile.open | tarslip.py:37:17:37:21 | tarfile.entry | Extraction of tarfile from $@ | tarslip.py:33:7:33:39 | Attribute() | a potentially untrusted source |
| tarslip.py:41:24:41:26 | tar | tarslip.py:40:7:40:39 | tarfile.open | tarslip.py:41:24:41:26 | tarfile.open | Extraction of tarfile from $@ | tarslip.py:40:7:40:39 | Attribute() | a potentially untrusted source |
| tarslip.py:59:21:59:25 | entry | tarslip.py:56:7:56:39 | tarfile.open | tarslip.py:59:21:59:25 | tarfile.entry | Extraction of tarfile from $@ | tarslip.py:56:7:56:39 | Attribute() | a potentially untrusted source |

30
python/ql/test/query-tests/Security/CWE-022/tarslip.py
View File

@@ -50,3 +50,33 @@ def safemembers(members):
tar = tarfile.open(unsafe_filename_tar)
tar.extractall(members=safemembers(tar))
# Wrong sanitizer (is missing not)
tar = tarfile.open(unsafe_filename_tar)
for entry in tar:
if os.path.isabs(entry.name) or ".." in entry.name:
tar.extract(entry, "/tmp/unpack/")
# OK Sanitized using not
tar = tarfile.open(unsafe_filename_tar)
for entry in tar:
if not (os.path.isabs(entry.name) or ".." in entry.name):
tar.extract(entry, "/tmp/unpack/")
# The following two variants are included by purpose, since by default there is a
# difference in handling `not x` and `not (x or False)` when overriding
# Sanitizer.sanitizingEdge. We want to ensure we handle both consistently.
# Not reported, although vulnerable to '..'
tar = tarfile.open(unsafe_filename_tar)
for entry in tar:
if not (os.path.isabs(entry.name) or False):
tar.extract(entry, "/tmp/unpack/")
# Not reported, although vulnerable to '..'
tar = tarfile.open(unsafe_filename_tar)
for entry in tar:
if not os.path.isabs(entry.name):
tar.extract(entry, "/tmp/unpack/")