TrojanSourceFinder helps developers detect "Trojan Source" vulnerability in source code.
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
Install
With go
> Via go install
Make sure $GOPATH
is in your $PATH
> From source
git clone https://github.com/ariary/TrojanSourceFinder
cd TrojanSourceFinder
make before.build
make build.tsfinder
If the command make build.tsfinder
failed, try:
env GOOS=target-OS GOARCH=target-architecture
go build -o tsfinder cmd/main.go
With curl
> From release
curl -lO -L https://github.com/ariary/TrojanSourceFinder/releases/latest/download/tsfinder && chmod +x tsfinder
Detect Trojan Source
> 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>:
Detect only in text file
> Source code files are likely text files. Withdraw them for scan could help to rule out false positives
Add -v
help to see which file has been skipped by scan.
Go further (Homoglyph)
Trojan Source is not new and isn't the only hazard. Another one is "Homoglyph".(Kezako?)
tsfinder help detecting them with homoglyph
command:
homoglyph [filename] [flags] ">
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 Trojan Source
> 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>
Demo
Homoglyph
Alternative
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 exitstatus 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 |