Merge pull request #2111 from HackTricks-wiki/update_Master_C_and_C___with_our_new_Testing_Handbook_cha_20260409_133740

Master C and C++ with our new Testing Handbook chapter

Author: carlospolop

src/network-services-pentesting/pentesting-web/code-review-tools.md

@@ -7,6 +7,85 @@
 - [**https://owasp.org/www-community/Source_Code_Analysis_Tools**](https://owasp.org/www-community/Source_Code_Analysis_Tools)
 - [**https://github.com/analysis-tools-dev/static-analysis**](https://github.com/analysis-tools-dev/static-analysis)
 
+## C/C++ Manual Review Gotchas
+
+When reviewing **C/C++** manually, look for APIs and patterns that appear safe in isolation but become exploitable when their outputs are reused later in the control flow.
+
+### Non-reentrant libc return buffers breaking security checks
+
+Some legacy networking/string helpers return pointers to **static internal storage**. A classic example is `inet_ntoa()`: storing the returned pointer and calling the function again usually means the second call overwrites the same buffer.
+
+```c
+char *user_ip = inet_ntoa(addr_from_user);
+char *allowed_ip = inet_ntoa(addr_from_policy);
+
+if (strcmp(user_ip, allowed_ip) != 0) {
+    return DENY;
+}
+```
+
+This kind of code can silently collapse an **allowlist / equality check** because both pointers may reference the same final string. During review, treat these APIs as suspicious whenever the returned pointer is:
+
+- stored for later comparison
+- reused across branches
+- relied on for policy decisions such as SSRF prevention or host allowlists
+
+Prefer APIs that write into a caller-provided buffer (`inet_ntop`, `snprintf`, explicit copies with fixed bounds).
+
+### Validated input reused later in `system()` / shell-outs
+
+A frequent review failure is validating input with a parser and later reusing the **original raw string** in a shell command:
+
+```c
+if (!inet_aton(ip_addr, &parsed)) {
+    return 1;
+}
+
+snprintf(cmd, sizeof(cmd), "ping '%s'", ip_addr);
+system(cmd);
+```
+
+Parsing the data does **not** make the original string safe. If execution reaches `system()`, `popen()`, `execl("/bin/sh", ...)`, or similar shell-backed helpers, metacharacters in the original input can still become **command injection / RCE**.
+
+During review, check for this sequence:
+
+1. Input is parsed or normalized into a structured object.
+2. A security decision is made using the parsed form.
+3. The original string is later passed to a shell.
+
+Safer patterns:
+
+- avoid the shell entirely
+- use `execve()`/`posix_spawn()` with a fixed argv array
+- derive the executed argument from the validated canonical form instead of the original input
+
+### User-controlled registry/config source steering kernel control flow
+
+In Windows driver code, a **user-chosen registry path** or similar configuration source should not directly influence privileged control flow. Review patterns such as:
+
+- `WdfRequestRetrieveInputBuffer` or IOCTL input supplying a registry path
+- `RtlQueryRegistryValues(..., RTL_QUERY_REGISTRY_DIRECT, ...)` writing directly into stack/local variables
+- queried values selecting callbacks, operation modes, or other security-sensitive branches
+
+If the attacker controls the key path, they often control not only the data but also the **value type, size, and presence/absence semantics**. That can turn a "read config and choose a callback" workflow into **reliable DoS** and sometimes a **kernel code execution primitive**.
+
+Red flags during review:
+
+- absolute registry paths accepted from user mode
+- no allowlist of trusted hives/keys
+- no strict type/length validation before copying into integers/structs
+- registry-derived values stored globally and later used as function pointers, dispatch selectors, or capability flags
+
+### Windows path handling footguns worth checking
+
+For Windows usermode reviews, explicitly audit for:
+
+- **unquoted path** issues in `CreateProcess*` call sites and service definitions
+- ANSI/Wide-char mismatches that let Unicode characters transform during path canonicalization
+- **WorstFit / Best-Fit** style issues where ANSI APIs reinterpret Unicode into separators or traversal primitives
+
+These are especially relevant when a path passes through validation in wide-char form but is later consumed by an ANSI API or command line builder.
+
 ## Multi-Language Tools
 
 ### [Naxus - AI-Gents](https://www.naxusai.com/)
@@ -455,7 +534,12 @@ https://github.com/securego/gosec
 - [https://jshint.com/](https://jshint.com/)
 - [https://github.com/jshint/jshint/](https://github.com/jshint/jshint/)
 
-{{#include ../../banners/hacktricks-training.md}}
+## References
 
+- [Trail of Bits blog: Master C and C++ with our new Testing Handbook chapter](https://blog.trailofbits.com/2026/04/09/master-c-and-c-with-our-new-testing-handbook-chapter/)
+- [Trail of Bits Testing Handbook: C/C++](https://appsec.guide/docs/languages/c-cpp/)
+- [DEVCORE: WorstFit - Unveiling Hidden Transformers in Windows ANSI](https://devco.re/blog/2025/01/09/worstfit-unveiling-hidden-transformers-in-windows-ansi/)
+
+{{#include ../../banners/hacktricks-training.md}}