Trojan Source vulnerability allows an attacker to make malicious code appear innocent.
In general, the attacker tries to lure by passing his code off as a comment (visually). It is a serious threat because it concerns many languages. Projects with multiple "untrusted" sources could be concerned
Detect evil 🔎
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Track evil 👀
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Trojan Source ❓
> Via go install
go install github.com/ariary/TrojanSourceFinder/cmd/tsfinder@latestMake sure $GOPATH is in your $PATH
> From source
git clone https://github.com/ariary/TrojanSourceFinder
cd TrojanSourceFinder
make before.build
make build.tsfinderIf the command make build.tsfinder failed, try:
env GOOS=target-OS GOARCH=target-architecture
go build -o tsfinder cmd/main.go> From release
curl -lO -L https://github.com/ariary/TrojanSourceFinder/releases/latest/download/tsfinder && chmod +x tsfinder> Help the detection of Trojan source for manual code review or with CI/CD pipelines (Unicode bidirectional characaters)
To detect Trojan source in file or directory <path>:
tsfinder [path]> Source code files are likely text files. Withdraw binaries for scan could help to rule out false positives
tsfinder -t [path]Add -v help to see which file has been skipped by scan.
Trojan Source is not new and isn't the only hazard. Another one is "Homoglyph".(Kezako?)
tsfinder help detecting them with homoglyph command:
tsfinder homoglyph [filename] [flags]You could see if there is a sibling (ie word with same "skeleton") for the homographs found in path using the flag --sibling:
tsfinder homoglyph [filename] --sibling [path] Functionality under development, mainly depending on other project
> Visualize how the code is really interpreted by machines/compiler
tsfinder is deliberately not very verbose. By default, it will only output if Trojan Source code has been detected. To have more verbosity and visualize the dangerous line add the flag -v.
To better see where Trojan Sources were, you could enable colored output with -c flag (also useful with directory scan):
tsfinder -c -v <directory>
As mentioned by @ioah86 here, trojan source could also been detected w/ a one liner using grep.
The big difference is the output format and the exit status code (tsfinder exit with status code 0 if no Trojan source has been found, 1 otherwise; the opposite for grep)
Also, this one-liner does not resolve the homoglyph issue
| Goal | tsfinder |
grep one-liner |
|---|---|---|
| Scan all files + show lines | tsfinder -v . |
grep -arE $'(\u2066|\u2067|\u2068|\u202A|\u202B|\u202D|\u202E|\u202C|\u2069|\u200E|\u200F|\u061C|\u2066|\u2067|\u2068)' |
| Scan only on human-readable files | tsfinder -t . |
grep -IrE $'(\u2066|\u2067|\u2068|\u202A|\u202B|\u202D|\u202E|\u202C|\u2069|\u200E|\u200F|\u061C|\u2066|\u2067|\u2068)' |
| Exit with status code 1 if found | default | [one-liner] && exit 1 || exit 0 |
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