Alphanumeric shellcode: Difference between revisions
Content deleted Content added
Fgnievinski (talk | contribs) No edit summary |
Fgnievinski (talk | contribs) merging into main article Tag: New redirect |
||
| Line 1: | Line 1: | ||
#REDIRECT [[Shellcode#Alphanumeric]] |
|||
In [[computer security]] '''alphanumeric shellcode''' is a [[shellcode]] that consists of or assembles itself on execution into entirely [[alphanumeric]] [[ASCII]] or [[Unicode]] characters such as 0-9, A-Z and a-z.<ref>{{cite web |last=SkyLined |url=http://www.phrack.org/issues.html?issue=57&id=15#article | title=Writing ia32 alphanumeric shellcodes |publisher=rix }}</ref><ref>{{cite web |last=SkyLined |url=http://www.phrack.org/issues.html?issue=61&id=11#article |title=Building IA32 'Unicode-Proof' shellcodes |publisher=obscou}}</ref> This type of encoding was created by [[Hacker (computer security)|hackers]] to hide working [[machine code]] inside what appears to be text. This can be useful to avoid detection of the code and to allow the code to pass through filters that scrub non-alphanumeric characters from strings (in part, such filters were a response to non-alphanumeric [[shellcode]] exploits). A similar type of encoding is called printable code and uses all [[Control character|printable]] characters (0-9, A-Z, a-z, !@#%^&*() etc...) It has been shown that it is possible to create shellcode that looks like normal text in English.<ref>{{cite web|url=http://www.cs.jhu.edu/~sam/ccs243-mason.pdf |author1=J. Mason |author2=S. Small |author3=F. Monrose |author4=G. MacManus |title=English shellcode |date=November 2009 |accessdate=2010-01-10}}</ref> |
|||
Writing alphanumeric or printable code requires good understanding of the [[instruction set architecture]] of the machine(s) on which the code is to be executed. It has been demonstrated that it is possible to write alphanumeric code that is executable on more than one machine.<ref>{{cite web |url=http://www.blackhatlibrary.net/Alphanumeric_shellcode |archive-url=https://web.archive.org/web/20120621124443/http://www.blackhatlibrary.net/Alphanumeric_shellcode |url-status=dead |archive-date=2012-06-21 | title=Multi-architecture (x86) and 64-bit alphanumeric shellcode explained |publisher=Blackhat Academy }}</ref> |
|||
==See also== |
|||
*[[EICAR test file]] - a test pattern used to test the installation of the anti virus software, which is written in printable code. |
|||
==Further reading== |
|||
* [http://www.phrack.org/issues.html?issue=57&id=15#article Writing ia32 alphanumeric shellcodes], an article on how to write alphanumeric shellcode. |
|||
* [http://www.phrack.org/issues.html?issue=61&id=11#article Building IA32 'Unicode-Proof' shellcodes], an article on how to write Unicode proof shellcode. |
|||
* [https://web.archive.org/web/20150403114315/http://skypher.com/wiki/index.php?title=Www.edup.tudelft.nl%2F~bjwever%2Fwhitepaper_shellcode.html.php Writing IA32 restricted instruction set shellcodes], an article on how to write code that is very limited in the number of characters it can use (such as alphanumeric code). |
|||
* [https://github.com/SkyLined/alpha3 ALPHA3], an alphanumeric shellcode encoder: Utility to encode normal machine code into alphanumeric (upper-case or mixed-case) ASCII or Unicode text. |
|||
* [https://web.archive.org/web/20110716082815/http://skypher.com/wiki/index.php?title=X86_alphanumeric_opcodes List of x86 Alphanumeric opcodes] |
|||
* [https://web.archive.org/web/20110716082850/http://skypher.com/wiki/index.php?title=X64_alphanumeric_opcodes List of x64 alphanumeric opcodes] |
|||
* [http://www.vividmachines.com/shellcode/shellcode.html#ps Shellcoding for Linux and Windows — Printable Shellcode]: Explanation and tutorial |
|||
== References == |
|||
{{reflist}} |
|||
{{DEFAULTSORT:Alphanumeric Code}} |
|||
[[Category:Computer security exploits]] |
|||
[[Category:Injection exploits]] |
|||
[[Category:Steganography]] |
|||
[[ca:Alfanumèric]] |
|||
Revision as of 21:54, 24 November 2021
Redirect to: