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Challenge Information - CROMU_00051

Commonly known as: Lazybox


Rounds Enabled

59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73

Details

Original Versions

Known Vulnerabilities

  • CWE-193 - Off-by-one Error
  • CWE-20 - Improper Input Validation
  • CWEs are listed as indicated by the challenge author.

Deployed patches

Deployed IDS rules

Author Information

"Joe Rogers" joe@cromulence.com

DARPA performer group

Cromulence (CROMU)

Description

This CB implements a basic shell and command line environment similar to busybox. It supports a single directory file system, the ability to create, delete and change between users, change user passwords, create files, and display their contents.

ShortDescription: A basic linux shell and command line environment

Feature List

The CB provides these features:

  • Basic shell with command history accessible through up/down arrows
  • Basic filesystem (single directory, list files, dump file contents)
  • User management (change user, change password, create new user, delete a user)
  • exit

Vulnerability

Vulnerability #1: The shell has a command history buffer with 16 entries. But, the PrependCommandHistory() function has an off-by-one error which allows 17 entries to be written. The CommandHistory buffer is stored in a structure directly adjacent to the User variable which determines the currently logged in user. If the CRS makes its first command one of the other defined users in the pre-confgiured password file (user 'root' or 'secure'), and then runs 16 more commands, the User variable will be overwritten with the username of their choosing. It's not immediately obvious that the username has been updated since the command history is prepended after the 17th command is entered.

Vulnerability #2: ':' characters are used as the field delimiter for the password file in the CB with the fields being "password:username:group". The 'passwd' command fails to check for ':' characters in user supplied passwords. So, it's possible to craft a fake 'root' user password file entry by changing the 'crs' user password to 'asdf:root:root' which will make the resulting password file entry "asdf:root:root:crs:crs". The extra fields at the end of the line are ignored by the 'su' command.

Generic class of vulnerability

Vulnerability #1: Incorrect array size calculation Vulnerability #2: Unchecked user input

CWE classification

Vulnerability #1: CWE-193 Off-by-one Error Vulnerability #2: CWE-20 Improper Input Validation

Challenges

The first vulnerability should be relatively easy to identify if the CRS sends more than 16 commands to the CB and correctly parses the CLI prompt which will change when the user name is overwritten. The CRS will then need to identify that the four bytes of secret flag data are stored in the 'secure' user's file and that the 'cat' command is the proper way to view that file's contents. Discovery: easy, Proving: easy, Fixing: easy.

The second vulnerability requires the CRS to identify the lack of input validation, understand the password file format, and figure out that the root user has the necessary access rights to the 'confidential' file even though it's owned by the 'secure' user. Discovery: medium, Proving: medium, Fixing: easy.


POV Information

Round Source Destination Result POV Analysis Video
60 CSDS CodeJitsu Failed POV POV Watch
60 CSDS DeepRed Failed POV POV Watch
60 CSDS Disekt Failed POV POV Watch
60 CSDS ForAllSecure Failed POV POV Watch
60 CSDS Shellphish Failed POV POV Watch
60 CSDS TECHx Failed POV POV Watch
60 DeepRed CodeJitsu Failed POV POV Watch
60 DeepRed CSDS Failed POV POV Watch
60 DeepRed Disekt Failed POV POV Watch
60 DeepRed ForAllSecure Failed POV POV Watch
60 DeepRed Shellphish Failed POV POV Watch
60 DeepRed TECHx Failed POV POV Watch
61 CSDS CodeJitsu Failed POV POV Watch
61 CSDS DeepRed Failed POV POV Watch
61 CSDS Disekt Failed POV POV Watch
61 CSDS ForAllSecure Failed POV POV Watch
61 CSDS Shellphish Failed POV POV Watch
61 CSDS TECHx Failed POV POV Watch
61 DeepRed CodeJitsu Failed POV POV Watch
61 DeepRed CSDS Failed POV POV Watch
61 DeepRed Disekt Failed POV POV Watch
61 DeepRed ForAllSecure Failed POV POV Watch
61 DeepRed Shellphish Failed POV POV Watch
61 DeepRed TECHx Failed POV POV Watch
62 CSDS CodeJitsu Failed POV POV Watch
62 CSDS DeepRed Failed POV POV Watch
62 CSDS Disekt Failed POV POV Watch
62 CSDS ForAllSecure Failed POV POV Watch
62 CSDS Shellphish Failed POV POV Watch
62 CSDS TECHx Failed POV POV Watch
62 DeepRed CodeJitsu Failed POV POV Watch
62 DeepRed CSDS Failed POV POV Watch
62 DeepRed Disekt Failed POV POV Watch
62 DeepRed ForAllSecure Failed POV POV Watch
62 DeepRed Shellphish Failed POV POV Watch
62 DeepRed TECHx Failed POV POV Watch
63 CSDS CodeJitsu Failed POV POV Watch
63 CSDS DeepRed Failed POV POV Watch
63 CSDS Disekt Failed POV POV Watch
63 CSDS ForAllSecure Failed POV POV Watch
63 CSDS Shellphish Failed POV POV Watch
63 CSDS TECHx Failed POV POV Watch
63 DeepRed CodeJitsu Failed POV POV Watch
63 DeepRed CSDS Failed POV POV Watch
63 DeepRed Disekt Failed POV POV Watch
63 DeepRed ForAllSecure Failed POV POV Watch
63 DeepRed Shellphish Failed POV POV Watch
63 DeepRed TECHx Failed POV POV Watch
64 CodeJitsu CSDS Successful POV POV Analysis Watch
64 CodeJitsu DeepRed Successful POV POV Analysis Watch
64 CodeJitsu Disekt Successful POV POV Analysis Watch
64 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
64 CodeJitsu Shellphish Failed POV through defenses POV Watch
64 CodeJitsu TECHx Successful POV POV Analysis Watch
64 CSDS CodeJitsu Failed POV through defenses POV Watch
64 CSDS DeepRed Failed POV POV Watch
64 CSDS Disekt Failed POV POV Watch
64 CSDS ForAllSecure Failed POV POV Watch
64 CSDS Shellphish Failed POV through defenses POV Watch
64 CSDS TECHx Failed POV POV Watch
64 DeepRed CodeJitsu Failed POV through defenses POV Watch
64 DeepRed CSDS Failed POV POV Watch
64 DeepRed Disekt Failed POV POV Watch
64 DeepRed ForAllSecure Failed POV POV Watch
64 DeepRed Shellphish Failed POV through defenses POV Watch
64 DeepRed TECHx Failed POV POV Watch
65 CodeJitsu CSDS Successful POV POV Analysis Watch
65 CodeJitsu DeepRed Successful POV POV Analysis Watch
65 CodeJitsu Disekt Successful POV POV Analysis Watch
65 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
65 CodeJitsu Shellphish Failed POV through defenses POV Watch
65 CodeJitsu TECHx Successful POV POV Analysis Watch
65 CSDS CodeJitsu Failed POV through defenses POV Watch
65 CSDS DeepRed Failed POV POV Watch
65 CSDS Disekt Failed POV POV Watch
65 CSDS ForAllSecure Failed POV POV Watch
65 CSDS Shellphish Failed POV through defenses POV Watch
65 CSDS TECHx Failed POV POV Watch
65 DeepRed CodeJitsu Failed POV through defenses POV Watch
65 DeepRed CSDS Failed POV POV Watch
65 DeepRed Disekt Failed POV POV Watch
65 DeepRed ForAllSecure Failed POV POV Watch
65 DeepRed Shellphish Failed POV through defenses POV Watch
65 DeepRed TECHx Failed POV POV Watch
66 CodeJitsu CSDS Failed POV through defenses POV Watch
66 CodeJitsu DeepRed Failed POV through defenses POV Watch
66 CodeJitsu Disekt Failed POV through defenses POV Watch
66 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
66 CodeJitsu Shellphish Failed POV through defenses POV Watch
66 CSDS CodeJitsu Failed POV through defenses POV Watch
66 CSDS DeepRed Failed POV through defenses POV Watch
66 CSDS Disekt Failed POV through defenses POV Watch
66 CSDS ForAllSecure Failed POV POV Watch
66 CSDS Shellphish Failed POV through defenses POV Watch
66 DeepRed CodeJitsu Failed POV through defenses POV Watch
66 DeepRed CSDS Failed POV through defenses POV Watch
66 DeepRed Disekt Failed POV through defenses POV Watch
66 DeepRed ForAllSecure Failed POV POV Watch
66 DeepRed Shellphish Failed POV through defenses POV Watch
67 CodeJitsu CSDS Failed POV through defenses POV Watch
67 CodeJitsu DeepRed Failed POV through defenses POV Watch
67 CodeJitsu Disekt Failed POV through defenses POV Watch
67 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
67 CodeJitsu Shellphish Failed POV through defenses POV Watch
67 CodeJitsu TECHx Failed POV through defenses POV Watch
67 CSDS CodeJitsu Failed POV through defenses POV Watch
67 CSDS DeepRed Failed POV through defenses POV Watch
67 CSDS Disekt Failed POV through defenses POV Watch
67 CSDS ForAllSecure Failed POV POV Watch
67 CSDS Shellphish Failed POV through defenses POV Watch
67 CSDS TECHx Failed POV through defenses POV Watch
67 DeepRed CodeJitsu Failed POV through defenses POV Watch
67 DeepRed CSDS Failed POV through defenses POV Watch
67 DeepRed Disekt Failed POV through defenses POV Watch
67 DeepRed ForAllSecure Failed POV POV Watch
67 DeepRed Shellphish Failed POV through defenses POV Watch
67 DeepRed TECHx Failed POV through defenses POV Watch
68 CodeJitsu CSDS Failed POV through defenses POV Watch
68 CodeJitsu Disekt Failed POV through defenses POV Watch
68 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
68 CodeJitsu Shellphish Failed POV through defenses POV Watch
68 CodeJitsu TECHx Failed POV through defenses POV Watch
68 CSDS CodeJitsu Failed POV through defenses POV Watch
68 CSDS DeepRed Failed POV through defenses POV Watch
68 CSDS Disekt Failed POV through defenses POV Watch
68 CSDS ForAllSecure Failed POV POV Watch
68 CSDS Shellphish Failed POV through defenses POV Watch
68 CSDS TECHx Failed POV through defenses POV Watch
68 DeepRed CodeJitsu Failed POV through defenses POV Watch
68 DeepRed CSDS Failed POV through defenses POV Watch
68 DeepRed Disekt Failed POV through defenses POV Watch
68 DeepRed ForAllSecure Failed POV POV Watch
68 DeepRed Shellphish Failed POV through defenses POV Watch
68 DeepRed TECHx Failed POV through defenses POV Watch
69 CodeJitsu CSDS Failed POV through defenses POV Watch
69 CodeJitsu Disekt Failed POV through defenses POV Watch
69 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
69 CodeJitsu Shellphish Failed POV through defenses POV Watch
69 CodeJitsu TECHx Failed POV through defenses POV Watch
69 CSDS CodeJitsu Failed POV through defenses POV Watch
69 CSDS DeepRed Failed POV through defenses POV Watch
69 CSDS Disekt Failed POV through defenses POV Watch
69 CSDS ForAllSecure Failed POV POV Watch
69 CSDS Shellphish Failed POV through defenses POV Watch
69 CSDS TECHx Failed POV through defenses POV Watch
69 DeepRed CodeJitsu Failed POV through defenses POV Watch
69 DeepRed CSDS Failed POV through defenses POV Watch
69 DeepRed Disekt Failed POV through defenses POV Watch
69 DeepRed ForAllSecure Failed POV POV Watch
69 DeepRed Shellphish Failed POV through defenses POV Watch
69 DeepRed TECHx Failed POV through defenses POV Watch
70 CodeJitsu CSDS Failed POV through defenses POV Watch
70 CodeJitsu Disekt Failed POV through defenses POV Watch
70 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
70 CodeJitsu Shellphish Failed POV through defenses POV Watch
70 CodeJitsu TECHx Failed POV through defenses POV Watch
70 CSDS CodeJitsu Failed POV through defenses POV Watch
70 CSDS DeepRed Failed POV through defenses POV Watch
70 CSDS Disekt Failed POV through defenses POV Watch
70 CSDS ForAllSecure Failed POV POV Watch
70 CSDS Shellphish Failed POV through defenses POV Watch
70 CSDS TECHx Failed POV through defenses POV Watch
70 DeepRed CodeJitsu Failed POV through defenses POV Watch
70 DeepRed CSDS Failed POV through defenses POV Watch
70 DeepRed Disekt Failed POV through defenses POV Watch
70 DeepRed ForAllSecure Failed POV POV Watch
70 DeepRed Shellphish Failed POV through defenses POV Watch
70 DeepRed TECHx Failed POV through defenses POV Watch
71 CodeJitsu CSDS Failed POV through defenses POV Watch
71 CodeJitsu Disekt Failed POV through defenses POV Watch
71 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
71 CodeJitsu Shellphish Failed POV through defenses POV Watch
71 CodeJitsu TECHx Failed POV through defenses POV Watch
71 CSDS CodeJitsu Failed POV through defenses POV Watch
71 CSDS DeepRed Failed POV through defenses POV Watch
71 CSDS Disekt Failed POV through defenses POV Watch
71 CSDS ForAllSecure Failed POV POV Watch
71 CSDS Shellphish Failed POV through defenses POV Watch
71 CSDS TECHx Failed POV through defenses POV Watch
71 DeepRed CodeJitsu Failed POV through defenses POV Watch
71 DeepRed CSDS Failed POV through defenses POV Watch
71 DeepRed Disekt Failed POV through defenses POV Watch
71 DeepRed ForAllSecure Failed POV POV Watch
71 DeepRed Shellphish Failed POV through defenses POV Watch
71 DeepRed TECHx Failed POV through defenses POV Watch
72 CodeJitsu CSDS Failed POV through defenses POV Watch
72 CodeJitsu Disekt Failed POV through defenses POV Watch
72 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
72 CodeJitsu Shellphish Failed POV through defenses POV Watch
72 CodeJitsu TECHx Failed POV through defenses POV Watch
72 CSDS CodeJitsu Failed POV through defenses POV Watch
72 CSDS DeepRed Failed POV through defenses POV Watch
72 CSDS Disekt Failed POV through defenses POV Watch
72 CSDS ForAllSecure Failed POV POV Watch
72 CSDS Shellphish Failed POV through defenses POV Watch
72 CSDS TECHx Failed POV through defenses POV Watch
72 DeepRed CodeJitsu Failed POV through defenses POV Watch
72 DeepRed CSDS Failed POV through defenses POV Watch
72 DeepRed Disekt Failed POV through defenses POV Watch
72 DeepRed ForAllSecure Failed POV POV Watch
72 DeepRed Shellphish Failed POV through defenses POV Watch
72 DeepRed TECHx Failed POV through defenses POV Watch
73 CodeJitsu CSDS Failed POV through defenses POV Watch
73 CodeJitsu DeepRed Failed POV through defenses POV Watch
73 CodeJitsu Disekt Failed POV through defenses POV Watch
73 CodeJitsu ForAllSecure Successful POV POV Analysis Watch
73 CodeJitsu Shellphish Failed POV through defenses POV Watch
73 CodeJitsu TECHx Failed POV through defenses POV Watch
73 CSDS CodeJitsu Failed POV through defenses POV Watch
73 CSDS DeepRed Failed POV through defenses POV Watch
73 CSDS Disekt Failed POV through defenses POV Watch
73 CSDS ForAllSecure Failed POV POV Watch
73 CSDS Shellphish Failed POV through defenses POV Watch
73 CSDS TECHx Failed POV through defenses POV Watch
73 DeepRed CodeJitsu Failed POV through defenses POV Watch
73 DeepRed CSDS Failed POV through defenses POV Watch
73 DeepRed Disekt Failed POV through defenses POV Watch
73 DeepRed ForAllSecure Failed POV POV Watch
73 DeepRed Shellphish Failed POV through defenses POV Watch
73 DeepRed TECHx Failed POV through defenses POV Watch
73 Disekt CodeJitsu Failed POV through defenses POV Watch
73 Disekt DeepRed Failed POV through defenses POV Watch
73 Disekt ForAllSecure Successful POV POV Analysis Watch
73 Disekt Shellphish Failed POV through defenses POV Watch
73 Disekt TECHx Failed POV through defenses POV Watch
73 Shellphish CodeJitsu Failed POV through defenses POV Watch
73 Shellphish CSDS Failed POV through defenses POV Watch
73 Shellphish DeepRed Failed POV through defenses POV Watch
73 Shellphish ForAllSecure Successful POV POV Analysis Watch
73 Shellphish TECHx Failed POV through defenses POV Watch

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