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[BUG] BD000700 (and BD000102) miss getattr-based dynamic calls

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
62/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
csharp, python
Domain
devtools, security

Research direction

Start by reading the BD000700 and BD000102 rule definitions and the rule matching path in the C# detector; the payload names data_exfiltration.json and code_execution.json. Then find the existing regression tests for these rules and run them. Add coverage for literal and constant getattr calls, and consider whether to implement the suggested patterns or normalization; done means both rules detect the reported dynamic forms without breaking existing matches.

Written by the indexing model from the issue text.

Description

Case Study

Literal attribute call (detected):

import requests

requests.get("http://evil.example/x")

Detected as: Security.Backdoor.DataExFiltration (rule BD000700, confidence Low).

Semantically identical dynamic dispatch in normal Python code, for example config-driven or plugin-driven code (not detected):

import requests

method = "get"
getattr(requests, method)("http://evil.example/x")

Result: "No tags were found."

Current rules

BD000700 (data_exfiltration.json): pattern is the regex

\.(request|post|get)\(

with scopes ["code","comment"] and confidence low.

BD000102 (code_execution.json): pattern is the string

requests.get

with scope code and confidence medium.

Both are pure text matches. The first requires the byte sequence ".get(" and the second requires "requests.get". Neither sequence exists in getattr(requests, method)(...), so the rules can never fire for a dynamic call. This also fails for the constant form getattr(requests, "get")(...).

Suggested Fix

Add a getattr variant, for example for BD000700:

getattr\s*\(\s*[\w.]+\s*,\s*['"](get|post|request)['"]\s*\)\s*\(

and for BD000102:

getattr\s*\(\s*requests\s*,\s*['"](get|post)['"]\s*\)

A more general fix is a small normalization pass that rewrites constant getattr(mod, "attr") calls to mod.attr (and folds constant attribute names) before rules run. Please add regression tests for both direct and getattr calls.

Reproduction results

Environment: OSSGadget 0.2.38 (ApplicationInspector), .NET 8, Windows.

Commands:

ossgadget detect-backdoor -f text ./ori
ossgadget detect-backdoor -f text ./adv

Results:

ori: Security.Backdoor.DataExFiltration (Low)
adv: No tags were found.

Attachments: ori.py, adv.py

adv.py
ori.py

Dominant language
C#
Stars
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Forks
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