Flawfinder – Source Code Auditing Tool


Flawfinder is a source code auditing tool that reports possible security weaknesses (flaws) sorted by risk level. It’s very useful for quickly finding and removing at least some potential security problems before a program is widely released to the public. It’s a static analysis source code auditing tool.

Flawfinder - Source Code Auditing Tool


Using Flawfinder Source Code Auditing Tool

It is specifically designed to be easy to install and use. After installing it, at a command line just type:

Also it works on Unix-like systems today (it’s been tested on GNU/Linux), and it should be easy to port to Windows systems. It requires Python 1.5 or greater to run (Python 1.3 or earlier won’t work).

Flawfinder Speed

Flawfinder is written in Python, to simplify the task of writing and extending it. Python code is not as fast as C code, but for the task I believe it’s just fine. The earlier version 0.12 on a 400Mhz Pentium II system analyzed 51055 lines in 39.7 seconds, resulting in an average of 1285 analyzed lines/second. Flawfinder 1.20 and later will report their speed (in analyzed lines/second) if you’re curious.

How Flawfinder works


Flawfinder works by using a built-in database of C/C++ functions with well-known problems, such as buffer overflow risks (e.g., strcpy(), strcat(), gets(), sprintf(), and the scanf() family), format string problems ([v][f]printf(), [v]snprintf(), and syslog()), race conditions (such as access(), chown(), chgrp(), chmod(), tmpfile(), tmpnam(), tempnam(), and mktemp()), potential shell metacharacter dangers (most of the exec() family, system(), popen()), and poor random number acquisition (such as random()). The good thing is that you don’t have to create this database – it comes with the tool.

It then takes the source code text, and matches the source code text against those names, while ignoring text inside comments and strings (except for directives). It also knows about gettext (a common library for internationalized programs), and will treat constant strings passed through gettext as though they were constant strings; this reduces the number of false hits in internationalized programs.

You can download Flawfinder here:

flawfinder-2.0.4.tar.gz

Or read more here.

Posted in: Secure Coding, Security Software

, , , ,


Latest Posts:


RandIP - Network Mapper To Find Servers RandIP – Network Mapper To Find Servers
RandIP is a nim-based network mapper application that generates random IP addresses and uses sockets to test whether the connection is valid or not with additional tests for Telnet and SSH.
Nipe - Make Tor Default Gateway For Network Nipe – Make Tor Default Gateway For Network
Nipe is a Perl script to make Tor default gateway for network, this script enables you to directly route all your traffic from your computer to the Tor network.
Mosca - Manual Static Analysis Tool To Find Bugs Mosca – Manual Static Analysis Tool To Find Bugs
Mosca is a manual static analysis tool written in C designed to find bugs in the code before it is compiled, much like a grep unix command.
Slurp - Amazon AWS S3 Bucket Enumerator Slurp – Amazon AWS S3 Bucket Enumerator
Slurp is a blackbox/whitebox S3 bucket enumerator written in Go that can use a permutations list to scan externally or an AWS API to scan internally.
US Government Cyber Security Still Inadequate US Government Cyber Security Still Inadequate
Surprise, surprise, surprise - an internal audit of the US Government cyber security situation has uncovered widespread weaknesses, legacy systems and poor adoption of cyber controls and tooling.
BloodHound - Hacking Active Directory Trust Relationships BloodHound – Hacking Active Directory Trust Relationships
BloodHound is for hacking active directory trust relationships and it uses graph theory to reveal the hidden and often unintended relationships within an AD environment.


3 Responses to Flawfinder – Source Code Auditing Tool

  1. d3m4s1@d0v1v0 September 16, 2009 at 7:00 pm #

    Another interesting tool to put in the bag.
    Finding potential buffer overflows before the program gets into production is a very critical task, it’s a shame that the programmers not always are aware of this…

  2. Andrew September 16, 2009 at 7:17 pm #

    What language(s) does it scan? Can I throw any source files at it, or is it just for C/C++?

  3. Jannich Brendle September 17, 2009 at 2:21 am #

    Andrew: Yes, flawfinder will only find flaws in C and C++ at the moment.