An attacker-controlled pointer free in Busyboxs hush applet leads to denial of service and possible code execution when processing a crafted shell command, due to the shell mishandling the &&& string. This may be used for remote code execution under rare conditions of filtered command input.
Weakness
The product calls free() on a pointer to memory that was not allocated using associated heap allocation functions such as malloc(), calloc(), or realloc().
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Busybox | Busybox | 1.33.0 (including) | 1.33.0 (including) |
| Busybox | Busybox | 1.33.1 (including) | 1.33.1 (including) |
| Busybox | Ubuntu | trusty | * |
| Busybox | Ubuntu | upstream | * |
| Busybox | Ubuntu | xenial | * |
Potential Mitigations
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, glibc in Linux provides protection against free of invalid pointers.
References
- https://claroty.com/team82/research/unboxing-busybox-14-vulnerabilities-uncovered-by-claroty-jfrog
- https://jfrog.com/blog/unboxing-busybox-14-new-vulnerabilities-uncovered-by-claroty-and-jfrog/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6T2TURBYYJGBMQTTN2DSOAIQGP7WCPGV/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UQXGOGWBIYWOIVXJVRKHZR34UMEHQBXS/
- https://security.netapp.com/advisory/ntap-20211223-0002/
- https://claroty.com/team82/research/unboxing-busybox-14-vulnerabilities-uncovered-by-claroty-jfrog
- https://jfrog.com/blog/unboxing-busybox-14-new-vulnerabilities-uncovered-by-claroty-and-jfrog/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6T2TURBYYJGBMQTTN2DSOAIQGP7WCPGV/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UQXGOGWBIYWOIVXJVRKHZR34UMEHQBXS/
- https://security.netapp.com/advisory/ntap-20211223-0002/