In Shadow 4.13, it is possible to inject control characters into fields provided to the SUID program chfn (change finger). Although it is not possible to exploit this directly (e.g., adding a new user fails because \n is in the block list), it is possible to misrepresent the /etc/passwd file when viewed. Use of \r manipulations and Unicode characters to work around blocking of the : character make it possible to give the impression that a new user has been added. In other words, an adversary may be able to convince a system administrator to take the system offline (an indirect, social-engineered denial of service) by demonstrating that "cat /etc/passwd" shows a rogue user account.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
| Attack Vector | LOCAL |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | LOW |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | NONE |
| Integrity Impact | LOW |
| Availability Impact | NONE |
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
CWE-74
|
| 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary |
en
CWE-125
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| shadow_project | shadow | 4.13 | <built-in method update of dict object at 0x7fd384e29600> | Application |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:a:shadow_project:shadow:4.13:*:*:*:*:*:*:* |